Rinse peppers and tomatoes and place whole in large pot of water to boil. Peel onion, cut into quarters and add to pot. Peel garlic cloves and add to pot whole. Boil for 45 minutes or until peppers are soft. Drain off water and allow to cool. Remove stems from peppers. If peppers are very hot (spicy) remove the seeds from half of them. Put in blender and blend, on coarse setting at medium speed, to desired consistency (usually less than 5-10 seconds.) You will need to blend three or four batches and then mix them together. Mix in chopped cilantro and salt to taste. Refrigerate. Makes 2 or 3 quarts.