Using a large mixing bowl, open the cans of olives and drain well. Then slice each olive into about 4 pieces..do that with both cans of olives. Then open jar olives, drain and slice also, add to bowl.
Chop tomatoes, onions and garlic and add to same bowl. Mix well. Then add the olive oil, red wine vinegar, salt and pepper and mix again.
It is best to let this sit in the fridge, covered, overnight, stir every now and then to blend flavors. Serve with Frito Scoops. I have also used tortilla chips, but everyone seems to like the Scoops the best.