The most important part of a good recipe is good ingredients. When in season we use locally grown, organic produce. When thats not an option, tomatoes on the vine are a good choice. They typically have a better flavor than others.
The key to dicing tomatoes is to use a very sharp knife. I typically use an 8" chef's knife that we sharpen/hone often. If your knife is dull and don't have a way to sharpen it use a serrated knife. Make sure you don't crush the tomatoes too much.
Cut the onion into pieces similar to the size of the diced tomatoes.
Chop the jalapeño very well, you want to feel the heat but not take big bites of it. We typically use half of 1 chili and it gives enough heat for us. If you're sensitive to heat, take out the seads and inner membrane, that's where the capsaicin is that causes the burn.
Combine all of your diced veg in a mixing bowl, add fresh chopped cilantro, lime juice and salt to taste. Add a little at a time until its the perfect ratio for your taste.
After everything is mixed and seasoned, cover your pico de gallo and put it in the fridge for 5-10 minutes. Remove it and drain the excess liquid. It is now ready to serve!