Prep the veg - Chop the onion into a small dice. Chop the garlic. Chop the pepper in to medium dice. Remove the core from the tomatoes and peel away any blemishes.
Add the tomatoes - Add the tomatoes, salt and sugar. Then stir in the tomato paste. Cook, stirring occasionally, until the tomato chunks have mostly melted into the sauce, and the sauce is thickened and not at all watery.