Preheat grill to high temperature.
Remove any stems from the tomatoes
Rub oil over each tomato and jalapeño.
Place tomatoes on hot grill. Cook for about 10 minutes.
Place jalapeños and onion pieces (use a basket or foil on the grates) onto the grill with the tomatoes. Cook for about 10 more minutes.
Turn the tomatoes and the peppers.
The tomatoes will turn partially black - when the skin begins to come off they are done.
When almost the entire surface of the peppers has charred black, remove them from the grill.
Remove onions.
Place all three on a plate and allow to cool. Drain off any accumulated liquid.
Remove stems from jalapenos and core ends of tomatoes.
Place cooled tomatoes, onions and jalapeño peppers into blender.
Add cilantro, pepper, salt and garlic.
Blend until desired consistency (approx 10 seconds).
Pour into container, cover and place in a refrigerator to chill or until ready to serve.
Serve and enjoy with your favorite chips.