Preheat oven to 450 F.
Roast the red bell pepper and cherry tomatoes for about 20-25 minutes, or until they are soft and the tomatoes are bursting.
Chop the onion and garlic and sauté for 5-7 minutes.
Peel the skin off of the bell pepper.
Add everything to your blender and add a tablespoon of pasta water at a time. Keep adding pasta water until you reach a thin consistency.
Add the sauce to a pot and simmer until it starts to thicken. Add in your pasta noodles and some veg if you like.