Diana Kennedy's Salsa de Jitomate del Norte (Northern tomato sauce)

2 large, red ripe tomatoes about 1 pound 1 1/2 teaspoons finely chopped cilantro or fresh coriander leaves 1/2 cup finely chopped onion Salt to taste, if desired 2 canned, peeled chilies, preferably Anaheim chilies 1 1/2 teaspoons white vinegar. 1. Preheat broiler. Place sheet of aluminum foil in baking dish and add tomatoes. Broil them, turning often, until outside skin is blackened and somewhat charred. Put tomatoes, skin and all, into container of food processor or blender and blend to fairly smooth but still a bit coarse puree. 2. Pour and scrape tomato puree into mixing bowl. Add remaining ingredients and blend well. Yield: About 2 1/2 cups.