Red wine vinegar
To get a good balance, start with the veggies (except the peppers). Get the veggie balance how you like it. Then add the spices & liquid ingredients to taste. Add the peppers last, just one at a time, until you’ve got it as hot as you want it.
Tip: slice an “x” in the bottom of the tomatoes & drop into boiling water, boil for about 30 seconds, then run under cold water & peel the skin off. Cut in half and scoop out the pulp & seeds.
Smash the garlic with a spoon before you cut it, this supposedly helps the flavor come out (I don’t know, it’s just what I’ve been told).
I usually put the garlic & cilantro in the blender with a few chunks of tomato & onion. Nobody really likes to bite into a chunk of garlic or a huge cilantro leaf :- )
Choose peppers based on how spicy you want your salsa. Jalapeños, Anaheims, Chiles, Habaneros… take your pick. Using the pepper’s seeds will increase the heat, so if you want it mild, don’t use the seeds.
Cut your veggies as large or as small as you like, I usually even put some of them in the blender to make chip dipping easier.
For the container of salsa I made today, I used about 4 or 5 roma tomatoes, 4 jalapeños, 1 white onion, 2 green onions, several sprigs of cilantro, 2 cloves of garlic, and 2 ears of grilled corn. Plus all the other ingredients, but I have no idea how much :- )