The bliss of the recipe is you can really do whatever you want. This is what I do, but you can change anything and do your own thing.
Chop up 1-2 tomatoes, 1 medium onion (1/2 of a big one), 1 avocado and a handful of cilantro. Mix together in a bowl. Dump in a rinsed can of black beans and a can of corn. Add salt and pepper to taste and a big splash of lemon juice. Grab a bag of chips and there you have it! YUM!