Roast peppers, stem and all, over the flame of a stove or on the grill; turn frequently until their skins are black. Place in a paper bag or steam for a few minutes in order to loosen the skin. Wash off the charred skin; destem and deseed. Destem and deseed chiles. Place peppers, onion, chiles, tomato paste, oil, and salt in a blender and puree until smooth. Serve with a good, crusty bread. Makes about 2 cups.