Cut the peppers, onion, and tomato into large chunks and remove the seeds from the peppers. Put them all into a glass baking dish large enough that all of the vegetables aren't too crowded. Put a few tablespoons of oil, some pepper and oregano and the can of Diced tomatoes on top then mix.
Take the two cloves of garlic, peel and remove the tops. Place them in some aluminum foil with a tablespoon of olive oil and wrap it closed.
Put the garlic and the glassware into the oven at 350F for around 45 minutes. You may want to mix it all up one or two times while it is cooking.
Put the garlic and the rest of the vegetables into a blender or food processor along with the can of tomato paste and blend until it is consistent. You may need to add a little water if it is too thick.
You may want to blanch the tomato and remove the skin before adding it in with the rest of the vegetables.
Makes a nice thick sauce that goes perfect with a big tube pasta like rigatoni.