In a medium bowl, mix the oil, garlic, lime juice and one half of the diced jalapeño peppers. Let it stand for 15 minutes to for the flavors blend.
Add the diced tomatoes, onion, cilantro and salt. Mix well and taste. Add additional salt and diced peppers to suit your taste.
Notes
Serrano peppers may be substituted for jalapeño peppers if you like it hot, Serrano peppers tend to be a bit spicier and 4 times hotter than jalapeño peppers. Both are good.