Oven Roasted Bell Peppers and Onions

These oven-roasted bell peppers and onions are one of the most versatile things you can make - tender, caramelized, and packed with flavor in just 30 minutes on a single sheet pan. Pile them into fajitas, layer them onto sandwiches, toss with pasta, or serve as a simple colorful side dish. Once you make them, you'll keep a batch in your fridge all week.

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Ingredients

This is such a simple side dish to make, but it is packed with flavor! You will need:

• Striped Holland Pepper (Green Bell Peppers works well too!)
• Orange Bell Pepper
• Red Bell Pepper
• Red Onion
• Olive Oil
• Crushed Red Pepper
• Salt & Pepper

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How to Roast Bell Peppers and Onions

There are just a few simple steps to make this delicious and colorful dish. In fact, the prep time is only 5 minutes! Preheat the oven to 400 degrees. Then, slice the peppers and red onions into strips that are about ¼ inch thick.

Arrange pepper and onion strips in a single layer on a large baking sheet.

Drizzle with a little olive oil and sprinkle with crushed red pepper. Then, add salt and pepper to taste. Toss the pepper and onion mixture to coat evenly.

Place in a preheated oven on the center rack and bake at 400 degrees Fahrenheit for 25 minutes.  Halfway through cook time, toss them and spread the peppers and onions back out in an even layer.

That is it! A simple, delicious and healthy side of veggies with a little bit of a kick in no time at all!

Ways to Serve Roasted Peppers and Onions

Roasted peppers and onions are endlessly versatile. Here are the most popular ways to use them:

• Fajitas - the classic use. Pile into warm tortillas with grilled chicken or steak, sour cream, and guacamole for an easy weeknight dinner
• Italian sausage sandwiches - layer onto a hoagie roll with sliced sausage for a street-fair classic at home
• Pasta - toss with penne, olive oil, and parmesan for a simple meatless dinner
• Rice bowls - serve over white or brown rice with your protein of choice for easy meal prep
• Eggs - add to scrambled eggs or an omelette for a savory, colorful breakfast
• Pizza topping - scatter over pizza dough before baking for a sweet roasted flavor
• On their own - honestly, straight from the pan with a little extra salt is hard to beat

How Long to Roast Peppers and Onions

At 400°F, roast peppers and onions for 25-30 minutes, stirring once halfway through. They're done when the edges are caramelized and slightly charred and the peppers are completely tender. If you prefer softer, more caramelized peppers, leave them in for the full 30 minutes. If you like a little more texture, pull them at 25 minutes.

Are Roasted Bell Peppers and Onions Healthy?

As a Registered Nurse, this is one of the side dishes I genuinely feel good about putting on the table. Bell peppers are one of the most nutrient-dense vegetables you can eat - a single red bell pepper delivers more than 150% of your daily Vitamin C, which supports immune function, skin health, and iron absorption. They're also rich in Vitamin A, potassium, and antioxidants including beta-carotene and quercetin.

Red onions add their own nutritional punch - they're one of the best dietary sources of quercetin, a flavonoid with anti-inflammatory properties that has been studied for its role in supporting heart health and immune response. Onions also contain prebiotic fibers that feed beneficial gut bacteria.

The olive oil in this recipe isn't just for flavor - it actually helps your body absorb the fat-soluble vitamins in the peppers more effectively. And at just 43 calories per serving with 3 grams of fiber, this is a side dish that genuinely earns its place on the plate.

Variations to try

Try different varieties of onions

I used red onion to make this dish. However, sweet onions, yellow onions or white onions also work well.

Add different seasoning

The ingredients were kept very simple here, but there are all sorts of ways to dress up this recipe. You could add in a ½ teaspoon of garlic powder to the existing recipe. Italian seasoning would also taste amazing tossed in with the peppers and roasted onions. Or you could even add some fresh basil before serving it.

Use different peppers

Try out different pepper varieties! I think this dish would taste great with poblano peppers or it would be fun to try with mini peppers.

How to Store Roasted Peppers and Onions

Store leftovers in an airtight container in the refrigerator for up to 4 days. They reheat well in a skillet over medium heat or in the microwave. Do not store at room temperature.

This post was originally published February 19, 2020 and updated March 25, 2026 with new tips, storage information, and frequently asked questions.