Place all the ingredients into a blender. Blend well so onions are cut up finely and all ingredients are mixed together well.
I have found to determine if the salsa is "perfect", it is better to taste it with a tortilla chip rather than with the sauce alone. Sometimes it is perfect the way the recipe is, other times I'll add more of the jalapenos, cilantro, vinegar, lime or salt depending on taste.
Let the salsa the set over night for best flavor. You can eat it after about an hour in the fridge, but over night is best.
This is one of those recipes you'll make a few times and modify to make your own perfect blend of salsa.