If you’re looking for an easy, make-ahead condiment that can elevate DOZENS of dinners, these slow roasted peppers and onions are where it’s at! They’re a cinch to make in the oven, making this a mostly hands-off recipe, and the result is a sweet, salty, bright condiment that will transform your next pizza night, barbecue, picnic, grilled cheese… (read on for more serving ideas!). 

Close up of roasted peppers and onions in a baking dish with a spoon.

Baked peppers and onions in oven 

While there’s nothing wrong with sautéed peppers and onions, baking peppers and onions in the oven is a game changer. It’s not only fuss-free, but it also turns the vegetables meltingly tender and sweet. 

Bell peppers, onion, garlic cloves and thyme on a countertop.
Bowl of baked peppers and onions.

Best peppers and onions recipe

Once out of the oven, the peppers and onions are finished with a splash of sherry vinegar, capers and fresh basil (the basil is optional). The vinegar provides balancing acidity, the capers lend a salty pop of flavor, and the basil provides herby freshness. They’re delicious enough to eat all on their own, and they add amazing flavor to dozens of dishes.

Slow roasted peppers piled over a seared chicken breast.

How to make roasted peppers and onions

  1. Thinly slice 1 sweet onion and 3 sweet bell peppers (you can use red, yellow and/or orange peppers) and place them in a 13×9-inch baking dish. 
  2. Toss the peppers with whole garlic cloves, thyme sprigs, salt and pepper. Toss to combine. 
  3. Roast the peppers and onions at 375˚F, stirring once or twice, until they are silky and tender, about 50-60 minutes. 
  4. Add sherry vinegar (or you can use red wine vinegar or white balsamic vinegar), capers (which are optional) and fresh basil (also optional). Toss to combine. 
Process shot showing sliced peppers and onions in a baking dish before baking.
Process shot showing peppers and onions in a baking dishing after roasting.

Sausage, peppers and onions

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 the sausages to a plate and cover them with foil to keep warm). Finish baking the vegetables until tender.   

How to serve peppers and onions

There are endless ways to serve these peppers and onions. For an easy appetizer, pile them over whipped ricotta crostini (check out this video to see how I do it!). You can layer them on grilled pork chops, grilled cheeses, in wraps and on burgers. For an easy, elegant and healthy dinner, I pile them over seared or grilled chicken breasts, then crumble feta cheese over top (YUM!). 

Peppers and onions with ricotta crostini.

FAQ

Can you make roasted peppers and onions ahead?

Yes! Slow roasted peppers and onions taste even better with time. They can sit at room temperature for up to 4 hours, and they can be refrigerated for up to 2 weeks! Store them with any juices and olive oil from the bottom of the pan. 

What type of onions and peppers do you use?

Use red, yellow and/or orange sweet bell peppers (green peppers are too bitter). I prefer to use sweet onions (such as Vidalia or Maui onions), but you can use regular white or red onions if that’s what you have.

How do you make sausage, peppers and onions?

To make sausage, peppers and onions, nestle uncooked sausages into the peppers and onions before baking.  

Roasted peppers over a cooked chicken breast, topped with feta cheese

Recipes with peppers and onions

You can serve the slow roasted peppers with dozens of dishes, from appetizers (think ricotta crostini!), to lunches (think grilled cheese!), to dinners (think grilled pork chops!). Eat them straight as a side dish, or pile them over dishes such as:

Peppers and onions on toasted baguette halves with ricotta cheese.

Tips for this recipe:

  • You’ll need a 9×13-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.   
  • The peppers and onions taste even better with time and can be refrigerated for up to 2 weeks!

Other recipes you might like:

Don’t forget dessert!

Get the recipe!

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

Ingredients

  • 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
  • 1/4 cup extra virgin olive oil
  • 1 tablespoon sherry vinegar
  • 2 tablespoons capers (optional)
  • 1/4 cup fresh basil leaves, thinly sliced (optional)

Instructions

  • Preheat the oven to 375˚F.
  • Put the sliced onion, peppers, garlic cloves and thyme sprigs in a 13×9-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.

Notes

Storage: The roasted peppers and onions can be refrigerated for up to 2 weeks. They taste even better with time!
Tips:
  • You’ll need a 9×13-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:

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