For a good un-cooked salsa, i don't measure anything but i put tomatoes, onion, peppers, cilantro, and a little salt in a food processor and pulse it a few times. You really can't mess it up and its good for you too.
I like mine uncooked too. Never measure anything. I did learn not to use a whole pound of fresh jalapenos! But I use everything fresh and uncooked. It is really good on a hot day. Sometimes if I feel like it I just chop everything with a knife. The blender makes it a little smoother but I always leave it with pieces. Chill all the ingredients and chill it when finished. Just play with it and then you will have to eat it.