In a skillet or grill basket, saut the beef strips, bell pepper strips and fajita or taco seasoning in olive oil for 5 to 7 minutes, or until beef has cooked through.
Prepare the ranch dressing, then stir in the lime juice, mashed avocado and cilantro leaves. Chill until ready to serve.
Once the beef and peppers have cooked, stir in the sour cream and cilantro leaves. Season with a little salt and pepper.
Add some beef and pepper mixture to the right third of the tortilla. Roll up, and spray the opposite side of the tortilla with cooking spray, so that it will hold tight together once you roll up all the way up. Roll tightly and place into a dish that you use to transfer them to the grill. Once they are all rolled up, fire up the grill and heat it to about 300, if you have a thermometer.
Grill the taquitos for 4-5 minutes on each side, watching carefully to make sure they dont burn. Carefully roll them with tongs or a long spatula. Once all sides have been grilled and tortillas are crispy, remove them from the grill and serve.
Serve Grilled Beef Taquitos with Avocado Ranch Sauce and desired side dish.