1 part onion
1 part peppers (pick variety based on heat you want, remove seeds to reduce heat)
1 bunch cilantro
4 parts tomatoes
lime juice
salt
black pepper
cumin
garlic (optional)

There are many variations on fresh salsa, and these amounts may not be precise. I like to make the salsa based on looks (the right amount of red against the green and white), and then just taste it on corn chips as I season it.

I personally love the taste of cilantro stems, so I find I can use less cilantro by using all of it.

You can food process all of the vegetables if you can pulse it. I like my salsa chunky so I don't puree it.