On the stove top, cook the onion and pepper in a couple of drizzles of olive oil until softened and lightly browned. Add the minced garlic, and saute for one additional minute. Season with salt and black pepper to taste.
Add beef, tomatoes and seasonings reserving cilantro to add at the end of cooking.
Simmer on low for about 15 minutes, until the tomatoes break down, and liquid evaporates. Remove from heat and mix in cilantro. Set aside.
Sprinkle cheese down the middle of each tortilla using one half divided equally between tortillas.
Divide the meat evenly between the tortillas over cheese. Top with remaining cheese.
Fold each side of the tortilla to the middle, and begin rolling up from the shortest end.
Spritz the tortilla liberally with olive oil or vegetable oil cooking spray on all sides, then lay seam side down on your preheated grill pan. You may also brush with oil, if desired.
Cook over medium-high heat until golden on all sides, pressing down gently with a spatula.
Serve immediately with lettuce, salsa and fresh guacamole.