Heat the olive oil in a large pan and sauté the onion until soft, about 5 minutes. Add the garlic and cook 30 seconds.
Add the chopped peppers and cook for 8 to 10 minutes, until soft.
Stir in the tomatoes, oregano, salt, pepper, and chili flakes if using. Simmer for 10 to 15 minutes, until thick.
Blend smooth with an immersion blender, or leave chunky.
Toss with cooked pasta and serve, with extra herbs on top.
Notes
Roast the peppers first for a smoky flavor. Stir in plant cream for a creamy version. Freezes up to 3 months. Nutrition value is just for the sauce, without pasta.