Place cilantro, pepper, garlic powder, and onion powder in the bowl of a blender. Pour in margarita mix, lime juice, orange juice, and agave. Puree on high speed until smooth. Reduce speed to medium-low, and slowly add 1 cup Mazola corn oil, continue blending until creamy.
Place chicken breasts in a resealable plastic bag or a large glass bowl, pour margarita marinade over the chicken, toss to coat chicken evenly. Refrigerate for 5 hours or up to 24 hours.
Heat 2 tbsp. Mazola corn oil in a large skillet.
Preheat oven to 425°F placing a rack in the middle of the oven.
Remove the chicken from marinade and sauté in large skillet for about 7 to 10 minutes, turning once. Cook until golden brown and internal temperature is 165°F. Remove chicken from skillet and cool. Once chicken is completely cooled, slice into thin strips and set aside.
For the taquitos:
Place tortillas on the baking sheet and put them in the warm oven for 3 to 5 minutes or until they are soft. When soft, place in a tortilla warmer.
Fill the tortilla with chicken, about ½ cup, roll tortilla and place seam side down on a baking sheet. Repeat with remaining tortillas.
Brush the taquitos with remaining Mazola corn oil and sprinkle with margarita salt.
Bake in a preheat oven 425°F for 10 to 12 minutes, or until golden brown and crispy. Remove from the oven and let cool for 3 to 4 minutes before serving.
Serve with a side of pico de gallo or fresh guacamole.