I owned a Mexican restaurant for about 20 years (real Mexican food from scratch). This is the salsa we served to our customers. I keep boiled whole jalapenos in my freezer. Catch them on sale, buy a boatload then just boil them til they're tender. Lay in single layer in freezer and once frozen dump them in a big ziplock so you can take out a few at a time. Salsa is a simple recipe but be sure and use fresh ingredients. When you buy fresh cilantro put it in water in the fridge like fresh flowers, keeps it looking good. The first batch of this salsa I use all the top of the cilantro bunch and the next batch I will use all the stems, they're just as flavorful but the whole kit n kaboodle is a bit much for this size batch.
Put in food processor: tomatoes with their juice, jalapenos, garlic, onion and pulse til just a little chunk left. Add the bunch of cilantro (either the leaves OR the stems), juice of fresh lemon and a good TBL spoon of salt, pulse to combine. Taste it and add more salt or lemon juice, it should have a nice bright flavor with some kick. It will heat up a bit by the next day. Keep in refrigerator, good to go for about a week.