Heat your grill to medium-high heat. Brush both sides of the tomatoes with olive oil. Place on grill and grill about 2 minutes per side or until they have softened slightly and have dark grill marks. Remove from grill. Set aside to cool.
While tomatoes are cooling combine the remaining ingredients for the salsa together in a bowl. Mix well. Once tomatoes are cool, dice them and add them to the rest of the ingredients. Mix well. Cover and let set at room temperature until ready to use.
Preheat oven to 350 degrees. Spray a baking sheet lightly with non-stick spray
Heat 1 tablespoon olive oil in a skillet over medium-low heat. Cook onions until they are brown and caramelized, 15 - 20 minutes. Remove from heat and set aside.
In the same skillet add the remaining tablespoon of olive oil and cook tortillas, one at a time, until soft and pliable. About 30 seconds on each side. Repeat with all tortillas.
In a bowl combine caramelized onions and pork. Mix well. Place a heaping tablespoon of the mixture in the center of a tortilla and roll up. Place the taquitos seam side down on the prepared baking sheet. Repeat with remaining ingredients until you've made 12 taquitos.
Cook taquitos in the preheated oven for 15 minutes. Sprinkle pepper jack cheese on top and return to the oven and cook until cheese has melted, about 5 minutes.
Place taquitos on a serving platter, top with shredded lettuce and grilled tomato salsa. Serve.