A few weeks ago, a friend was having a dinner party and asked everyone to bring something to put in a salsa. (As I didn't know what went in a salsa, I brought corn chips.) After watching her make the salsa, I went home and tried it myself. I didn't remember the recipe exactly, and it's not important. Just put all of the following in a blender in whatever quantities you like - mostly tomatoes, of course:
tomatoes (I use fresh, but canned will do)
chilies (I put three different kinds in mine, whatever the supermarket has)
onion (just a tiny bit)
cilantro (a.k.a. coriander for Australian readers) (use lots!)
lime juice (I prefer more rather than less, because I love citrus)
Pulse until it becomes a mulchy mess and EAT.