About 3 Roma tomatoes
1 smallish jalapeno pepper
1/2 small onion (white onions are traditional, but I love the color and flavor of red onions)
Freshly squeezed lime juice (use 1/2 lime for a little zing, use the whole thing for distinct lime flavor. In case you were wondering, I use the whole thing)
A very generous pinch of chopped cilantro–I just grab some using all my fingers at once. It probably comes out to about 1/4 c.
Kosher salt to taste; some people leave it on the bland side because a lot of foods pico de gallo is served with tends to be salty. Personally, I like it on the salty side.