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+ servings

Easy Slow Roasted Peppers and Onions

These slow roasted peppers and onions are silky and sweet, with brightness from sherry vinegar and capers. Pile them over sausages, chicken, fish, burgers, pizza, sandwiches, and more (see below for serving suggestions)!!
Prep Time15 mins
Cook Time1 hr
Total Time1 hr 15 mins
Course: Side Dish
Cuisine: American
Keyword: peppers and onions, peppers and onions recipe, roasted peppers and onions
Servings: 6 people


  • 1 large sweet onion, thinly sliced
  • 3 sweet bell peppers (red, yellow and/or orange), thinly sliced
  • 3 garlic cloves, lightly smashed and peeled
  • 2 large thyme sprigs
  • Salt and freshly ground black pepper
  • ¼ cup extra virgin olive oil
  • 1 tablespoon sherry vinegar
  • 2 tablespoons capers (optional)
  • ¼ cup fresh basil leaves, thinly sliced (optional)


  • Preheat the oven to 375˚F.
  • Put the sliced onion, peppers, garlic cloves and thyme sprigs in a 13x9-inch (or similar sized) baking dish, and season with salt and pepper. Drizzle with the olive oil, and toss to combine. Bake the vegetables, stirring a few times during cooking, until silky and tender, about 50-60 minutes.
  • Discard the thyme sprigs. Drizzle the vegetables with the sherry vinegar, and stir in the capers and basil (if using). Toss to combine. Season with salt and pepper as needed.
  • Transfer the peppers and onions to a bowl or jar (make sure you include any juices from the bottom of the pan!). Serve warm or at room temperature.


Storage: The roasted peppers and onions can be refrigerated for up to 2 weeks. They taste even better with time!
  • You’ll need a 9x13-inch or similar sized baking dish for this recipe.
  • In place of the sherry vinegar, you can use red wine vinegar, white balsamic or a mix of half balsamic and half white wine vinegar instead. 
  • To make sausage, peppers and onions, nestle whole, uncooked Italian sausages (you can use pork, chicken or turkey) in the pepper and onion mixture, then bake as directed. Check the sausages starting at 30 minutes, and remove them once they’re cooked through (transfer them to a plate and cover them with foil to keep warm). Finish baking the peppers and onions until tender.   
Serving Suggestions:
Serve the peppers and onions on their own as a side dish, or pile them over dishes such as: