Roasted onions with thyme and rosemary are a tasty side that anyone can enjoy. They’re simple to prepare but pack a real punch of flavor, which makes them an exciting addition to your meal.
This recipe provides solutions for achieving tender, flavorful roasted onions while avoiding issues like uneven cooking and inadequate seasoning in simpler side dishes.
I’ve faced the challenge of getting my kids to eat more veggies, and these roasted onions do the trick! Their sweet taste and savory herbs make them hard to resist. Plus, they cook in just about 45 minutes, which fits perfectly into a busy weeknight dinner.
What I love about this recipe is its ease. You just slice the onions, drizzle them with olive oil, and toss in some fresh herbs. Then, pop them in a hot oven until they’re golden brown and tender. If you want an even more flavorful dish, be sure to try these alongside my onion bagels!
Table of contents
Why You Will Love This Recipe
- Incredible Aroma , Roasting onions fills your kitchen with a warm, inviting scent that promises a comforting meal. The combination of sweet yellow onions with fresh herbs creates an irresistible smell that makes everyone eager to dig in.
- Perfectly Tender , The oven’s heat transforms these onions into soft, caramelized delights. Roasted for about 40-45 minutes, they become tender and slightly sweet, offering a satisfying texture that complements any dish.
- Simple and Quick Prep , It only takes about 5 minutes to prep the onions, making this dish a breeze for busy cook nights. Just slice, season, and let the oven do the work while you focus on the rest of the meal.
- Herbal Freshness , The addition of thyme and rosemary elevates the flavor profile, adding a fragrant herbal note that pairs beautifully with the sweetness of the onions. This herbaceous kick makes it a standout side that adds depth to any plate.
Roasted Onions with Thyme and Rosemary
- Prep Time: 5 minutes
- Cool Time:
- Cook Time: 45 minutes
- Total Time: 50 minutes
- Yield: 4 servings 1x
- Category: side dish
- Method: roasting
- Diet: Low Fat
Description
Delicious roasted onions with herb butter, perfect as a side dish or flavor enhancer for various meals.
Ingredients
Scale
- 4 medium (about 2–3 inches / 5-7.5 cm each) sweet yellow onions or Vidalia onions
- 3 tablespoons (44 ml) extra virgin olive oil
- 2 tablespoons (28 g) unsalted butter
- Kosher salt, to taste
- Fresh ground black pepper, to taste
- Fresh thyme leaves, to taste (chopped)
- Fresh rosemary, to taste (chopped)
- Optional: Balsamic vinegar, a splash (about 1 teaspoon / 5 ml), can substitute with red wine vinegar
Instructions
- Step 1: Preheat your oven to 400°F (200°C). Line a small baking sheet with parchment paper to help with cleanup and ensure even roasting.
- Step 2: Cut each onion in half from root to tip. Peel off the outer dried layers carefully. Arrange the onion halves on the prepared baking sheet, cut side up, in a single layer to ensure even cooking and flavor absorption.
- Step 3: Drizzle approximately 3 tablespoons of extra virgin olive oil evenly over the onion halves. Place a small pat (about 1/2 tablespoon or 7 g) of unsalted butter on top of each onion half to enhance browning and flavor depth.
- Step 4: Sprinkle each onion half generously with kosher salt and freshly ground black pepper to taste. Add a scattering of fresh thyme leaves and chopped fresh rosemary over the top of the onions to impart a fragrant herbal aroma and flavor.
- Step 5: Place the baking sheet in the preheated oven and roast the onions for 40-45 minutes. They should turn golden brown and become tender when pierced with a fork. About 20 minutes into roasting, if onions begin to brown too quickly, loosely cover them with aluminum foil to prevent burning while allowing continued cooking. Check at approximately 20-25 minutes and rotate the baking sheet to promote even cooking and browning. If onions are not yet tender after 45 minutes, continue roasting for up to an additional 5 minutes, checking frequently to avoid over-browning. Adjust roasting time longer if using larger onions or different varieties, up to 50 minutes as needed.
- Step 6: Once the onions are tender and golden brown, remove from oven. Sprinkle a final portion of fresh thyme and chopped rosemary over them to refresh the herbal flavor and aroma just before serving.
Notes
- Room Temperature: Store roasted onions in an airtight container at room temperature for up to 2 days, avoiding direct sunlight or heat sources.
- Refrigeration: Allow onions to cool before placing them in an airtight container. Refrigerate for up to 4 days to retain texture and freshness.
- Freezing: Wrap cooled onions tightly in plastic wrap, then seal inside a freezer bag or airtight container. Freeze for up to 3 months. Thaw refrigerated overnight before reheating.
- For stronger herb flavor, sprinkle an additional teaspoon of fresh thyme and rosemary 15 minutes before finishing roasting.
- If brown spots develop too quickly, cover onions loosely with foil around 20 minutes into baking to prevent burning while continuing slow cooking.
- Rotate the baking sheet halfway through roasting for even heat distribution and consistent caramelization.
- Larger onions require longer roasting times; monitor tenderness by gently piercing to avoid undercooked centers.
- Use sweet onion varieties like Vidalia or Walla Walla for natural caramelization and balanced sweetness.
- Choosing fresh thyme with vibrant green leaves and fresh, flexible rosemary needles will maximize freshness and herbal aroma.
- Extra virgin olive oil adds richness and aids in achieving a nice caramelized crust on the onions.
- Reheat onions in a 350°F (175°C) oven for about 10 minutes or until warmed through. Alternatively, reheat gently in a skillet over medium-low heat until heated. Avoid high heat reheating to prevent burning or drying out.
- Serve blooming baked onions as a side dish with grilled chicken breasts, pork chops, or roasted meats for a balanced meal.
- Pair with grains such as quinoa or couscous for added texture and a hearty plate.
- Add to vegetable soups, grain bowls, or salads to infuse flavor and natural sweetness.
- For extra depth, drizzle with balsamic glaze or sprinkle with crumbled feta cheese before serving.
- A light drizzle of herb-infused olive oil over onions before serving adds brightness and richness.
- Substitute balsamic vinegar (approximately 1 teaspoon) or red wine vinegar as a finishing drizzle to add acidity and balance the onion’s sweetness.
- Add a teaspoon of finely chopped garlic or minced shallots for additional savory complexity before roasting.
- Use different fresh herbs such as sage or oregano to vary the herbal notes to preference.
- Choose sweet onions like Vidalia or Walla Walla for their natural sugar content, which caramelizes well and enhances the dish’s flavor.
- Fresh thyme should be vibrant green and leafy for the best flavor; dried thyme is less potent and not recommended for this recipe.
- Fresh rosemary needs to be bright green with flexible needles; woody or brown needles indicate old or stale herbs.
- Use good quality extra virgin olive oil to impart richness and aid baking browning.
- Butter adds needed fat and caramelization; unsalted butter allows precise salt control during seasoning.
- If balsamic vinegar is included, a splash (1 teaspoon) complements the sweetness of the onions without overpowering.
Nutrition
- Serving Size: 1 onion half
- Calories: Not specified
- Sugar: Not specified
- Sodium: Not specified
- Fat: Not specified
- Saturated Fat: Not specified
- Unsaturated Fat: Not specified
- Trans Fat: Not specified
- Carbohydrates: Not specified
- Fiber: Not specified
- Protein: Not specified
- Cholesterol: Not specified
Ingredient Notes
- Onions: Go for sweet onions like Vidalia or Walla Walla. Their natural sugars caramelize beautifully, enhancing the dish’s flavor.
- Fresh thyme: Opt for vibrant green leaves, as they have a fresher taste than dried. This herb adds a lovely earthy profile that complements the onions.
- Fresh rosemary: Look for bright green, flexible needles. Fresh rosemary brings a unique woodsy aroma that elevates the overall dish.
- Olive oil: Use a good quality extra virgin olive oil for drizzling. It adds richness and enhances the roasting process, helping to achieve a nice caramelization.
- Balsamic vinegar: A splash will enhance acidity and balance the sweetness of the onions. If unavailable, a dash of red wine vinegar works as a substitute.
- Onions: Go for sweet onions like Vidalia or Walla Walla. Their natural sugars caramelize beautifully, enhancing the dish’s flavor.
- Fresh thyme: Opt for vibrant green leaves, as they have a fresher taste than dried. This herb adds a lovely earthy profile that complements the onions.
- Fresh rosemary: Look for bright green, flexible needles. Fresh rosemary brings a unique woodsy aroma that elevates the overall dish.
- Olive oil: Use a good quality extra virgin olive oil for drizzling. It adds richness and enhances the roasting process, helping to achieve a nice caramelization.
- Balsamic vinegar: A splash will enhance acidity and balance the sweetness of the onions. If unavailable, a dash of red wine vinegar works as a substitute.
Recipe Tips
- If the onions brown too quickly, cover them loosely with foil about 20 minutes into roasting. This protects them while allowing continued cooking without burning.
- For uneven cooking, check the onions halfway through and rotate the baking sheet. This ensures even heat distribution for consistent roasting.
- If the onions aren’t tender after 45 minutes, continue roasting for an additional 5 minutes. Check often to prevent over-browning and to ensure desired doneness.
- When using different onion varieties, adjust the roasting time based on size, larger onions may need up to 50 minutes. This avoids undercooked centers.
- If you desire a stronger herb flavor, sprinkle a teaspoon of fresh thyme and rosemary 15 minutes before removing them from the oven. This intensifies the herbal notes.
Serving Suggestions
Serve roasted onions alongside grilled chicken or pork chops for a hearty meal. Pair them with quinoa or couscous for extra texture and flavor.
Add roasted onions to vegetable soups or grain bowls for a burst of flavor. Use them in salads for added nutrition and sweetness.
Top roasted onions with balsamic glaze or a sprinkle of feta cheese for depth. A drizzle of herb-infused olive oil offers richness and brightness.
Recipe variations
- You can use sweet yellow or Vidalia onions for roasting, selecting 4 medium onions to provide the ideal sweetness and texture in this recipe.
- Add 3 tablespoons olive oil and 2 tablespoons butter, then season with kosher salt and freshly ground black pepper, plus fresh rosemary and thyme to taste for herbal depth.
- Either prepare onions by peeling and halving, or substitute with shallots if preferred; both work well for roasting with herbs and butter for flavor.
- If making for more servings, increase onions by multiples of 4 and adjust olive oil and butter accordingly; roast in batches on parchment-lined trays for best results.
Save This Recipe!
How to Store?
To keep your roasted onions fresh and delicious, follow these storage tips:
Room Temperature: Place roasted onions in an airtight container, store at room temperature up to 2 days, avoiding direct sunlight or heat sources.
Refrigeration: Transfer to an airtight container, refrigerate for up to 4 days. Allow onions to cool before sealing to retain texture.
Freezing: Wrap cooled onions tightly in plastic wrap, place in a freezer bag or container, freeze up to 3 months. Thaw refrigerated before reheating.
Other Recipes You’ll Love
- Classic Pumpkin Loaf
- Pumpkin Cream Cheese Scones
- Pumpkin Cream Cheese Cinnamon Rolls
- Pumpkin Cream Cheese Bundt Cake
If you enjoyed this roasted onions or any other recipe on my blog, please leave a ⭐ star rating and let me know how it went in the comments below. I appreciate taking time to read about this recipe, thank you!
