First up, get out your trusty gloves, you don't want to be messing with jalapeno's unless you're properly covered up. Trust me on this one. It is very important, unless of course you're into pain, at which point just go ahead and disregard this. Just kidding, but I've made the mistake of rubbing an eye when I've had Jalapeno juice on my hand and the agony, totally not worth it.
Start by getting your ingredients together. And nothing in this is really exact because you'll be making this for you, and whatever your heat tolerance is.
You want some lovely fresh jalapeno peppers, a couple of tomatoes, an onion, cilantro, lime and salt. Start by dicing up a Roma tomato or two, depending on how much you are making, you want a fairly fine dice, then dice up a white onion, again a fairly fine dice. And now for the fun, depending on your tolerance or love of heat, you want to mince or very finely dice 1-3 jalapeno's. Start by whacking off the stem end, slicing them in two lengthwise and then cutting out the seed and membrane.
Add all together and stir, squeeze the juice of a lime over it, add a handful of finely chopped cilantro
and about a half teaspoon of salt, or less to start. Stir it all up and taste. You can always add more jalapeno's or tomatoes or any portion to make it to your taste. This is your Pico de Gallo after all.