OK- Define salsa! Do you mean a pico de gallo or a taco sauce? I'll give you both.
Taco sauce: Cut up your tomatoes into quarters or so and put in a stew pot. Add two onions, coarsely chopped. A teaspoon of cumin, two teaspoons of garlic (less if a small batch), 1/2 cup chopped cilantro (All spices mentioned are fresh=use dried if you have to!), a teaspoon of oregano and a teaspoon of coriander seeds ground (use a clean coffee grinder or mortar and pestle. Freshly ground has a delightful, citrus odor). Of course, several dashes of Tabasco sauce. Depending on desired spiciness, add peppers.
For pretty mild: add two to four jalapenos with seeds and veins removed.
For pretty hot: two to four jalapenos with seeds and veins intact and a couple of chopped serranos.
My "six-pack from hell" (about as spicy as I can take): six habaneros, six chipotles (dried preferred, or canned). six jalapenos, six serranos, 6 poblamos , six dashes of Tabasco sauce. Remove only stems from the peppers. This equals six different peppers and six of each.
After stewing, run through a blender. Serve as desired.
For pico de gallo (a chopped salsa):
Dice 6-8 tomatoes, excluding stems, add 1-2 diced jalapenos (without seeds or veins), 1 teaspoon garlic, 2-4 dashes of cumin, i/2 teaspoon coriander seeds, 1/2 cup fresh cilantro, 1 teaspoon fresh oregano, juice from 2 limes, salt and pepper to taste, 1/2 cup green onion. Vary ingredients as you like. Add some hot sauce to spice it up, if you wish. Or puree a couple of tomatoes, if you wish. Oh, as always, a couple of dashes of Tabasco sauce. I also add a 1/2 teaspoon of a Habanero sauce (bottled). Serve with fresh chips.