Roasted Tomatoes and Onions with Garlic and Herbs
A simple yet elegant roasted vegetable dish that transforms fresh tomatoes and red onions into caramelized, tender components through gentle oven heat. This Mediterranean-inspired preparation relies on quality ingredients and minimal seasoning to let natural flavors shine. Beef tomatoes and red onions develop sweet, jammy notes when roasted, while garlic softens into creamy sweetness and thyme and oregano provide herbaceous depth. The dish suits anyone seeking straightforward, healthy cooking with minimal hands-on time. Perfect as a side dish for grilled proteins, tossed into pasta, spooned over crusty bread, or served at room temperature as part of a Mediterranean spread. What distinguishes this version is its two-stage roasting method, which allows onions to caramelize before tomatoes are added, preventing them from drying out while ensuring balanced texture throughout.
Ingredients
- 4 beef tomatoes, halvedRoma tomatoes1:1none
Roma tomatoes are smaller; reduce total roasting time by 5-10 minutes
- 3 red onions, cut into wedgesyellow onions1:1none
Yellow onions are milder and slightly sweeter; flavor will be less sharp
- 1 clove garlic, thinly sliced
- 2 tablespoons fresh thyme, or drieddried thyme1:3reduces:fresh
Dried thyme concentrates flavor; use one-third the fresh amount
Full guide → - 1 ½ tablespoon olive oil, divided
- 2 teaspoons dried oreganofresh oregano1:3reduces:dried
Triple fresh oregano quantity; add after roasting to preserve brightness
Full guide → - salt, to taste(optional)
Instructions
- 1
Slice the garlic into thin slices
- 2
Cut the red onions into wedges
- 3
Halve the tomatoes
- 4
Toss the onions with garlic, thyme, and one portion of olive oil, then spread onto a parchment-lined baking sheet
- 5
Preheat the oven and roast the onion mixture in the center rack for 15 minutes
- 6
Remove the baking sheet from the oven and stir the onions
- 7
Arrange the tomato halves cut-side up among the onions and season with oregano and salt
- 8
Drizzle the tomatoes with remaining olive oil
- 9
Roast in the center of the oven for another 15 minutes
Tips
Use a parchment-lined baking sheet to prevent sticking and ensure easy cleanup. This also allows hot air to circulate underneath, helping vegetables caramelize evenly on all sides.
Stir the onions halfway through cooking so they soften uniformly and develop color. Adding tomatoes after the first roast prevents them from becoming mushy while onions finish caramelizing.
Serve at room temperature for deeper flavor. The vegetables continue to develop taste as they cool, making this excellent for preparing ahead and serving later in the day.
Good to Know
Refrigerate in an airtight container for up to 4 days. Bring to room temperature or gently reheat before serving.
Prepare through step 6 up to 8 hours ahead. Cover and refrigerate, then add tomatoes and complete final roasting just before serving.
Serve warm or at room temperature as a side dish, over crusty bread, with grilled meats, or as part of a Mediterranean antipasto spread.
Common Mistakes
Skip stirring the onions halfway through to avoid uneven browning and undercooked centers in thicker pieces.
Substitutions
Roma tomatoes are smaller; reduce total roasting time by 5-10 minutes
Full guide →Dried thyme concentrates flavor; use one-third the fresh amount
Full guide →Yellow onions are milder and slightly sweeter; flavor will be less sharp
Triple fresh oregano quantity; add after roasting to preserve brightness
Full guide →FAQ
Can I use cherry tomatoes instead of beef tomatoes?
Yes, but reduce the final roasting time to 8-10 minutes since cherry tomatoes are smaller and contain less water. Watch carefully to prevent them from bursting or becoming too soft.
What if I don't have fresh thyme?
Use one teaspoon dried thyme instead, as dried varieties concentrate flavor. Alternatively, substitute dried basil or Italian seasoning at the same ratio. Adjust to taste.
How long do roasted tomatoes and onions keep in the refrigerator?
Store in an airtight container for up to 4 days. The vegetables soften slightly over time but remain flavorful. Bring to room temperature or warm gently before serving.