Put 1 can of tomatoes in a blender. Pulse just enough to make a coarse sauce; this is the base of the salsa.
Empty blender container into a large serving bowl. Coarsely chop the onions, tomatoes (canned and fresh), and peppers and add to the bowl along with the canned chilies.
Add remainder of ingredients. Salt and pepper to taste.
Stir to mix well. Serve as an appetizer with corn chips or to spice up your favorite Mexican dish.
For milder salsa, the jalapeno may be omitted.