Preheat oven on Broiler with top rack installed. Prepare ice bath in large bowl.
Place fresh tomatoes, onion, jalapenos and garlic on half sheet plan. Drizzle with EVO. Put high on rack under broiler 10-12 minutes or until charred well. Remove and place veggies in gallon ziplock and submerge in ice water for a few minutes.
Remove cooked tomato skins. In food processor, add everything from bag, the cilantro, cumin, salt, agave, 7UP. Pulse a few times. We don't want to puree! Now add whole canned tomatoes and raw onion & garlic . Pulse a few times more till you have desired consistency.
Notes
Adjust for spiciness by adding a few pieces of raw serrano or jalapeno in food processor.