Peel and seed avocado's. Put in large bowl and mash(if you like chunks, leave some chunks.)
Chop, or dice onions and tomatoes.
Add all to avocado's, stir, s&p to taste. If you like it a little creamier, add a little more sour cream. Not so creamy, less sour cream. Your done. Tweak it to your own taste. That's what I do to any recipe.