First of all, I personally only use red and/or yellow peppers, not green, although some Italian recipes will include green peppers. I also choose the long, rather misshapen fellows over the perfect bell-shaped ones, which tend to be less tasty. See photo.
So. Take 6 red and yellow peppers. Clean and cut into strips that are about half an inch thick and two-three inches long. Put about four Tbsp. extra-virgin olive oil in large pan, saute' a garlic clove until golden, remove. Add 1 large onion (Vidalia would be nice) cut into thin slices, saute' briefly while stirring. Add pepper strips. At this point you can either add one cup of diced tomatoes, or (and this is what I do) add an 8-oz. can of the ole Hunt's tomato sauce. Cook until peppers are limp; they should not be al dente. Stir from time to time and keep a cup of water on hand to regulate liquidity. Season to taste. Add one Tbsp. of vinegar at the end (optional).
This is good as a side with chicken or even hard-boiled eggs. It can also be used as a pasta or crusty bread topping.