In a food processor, combine lime juice, tequila, olive oil, cilantro, garlic, salt and pepper. Process until smooth. In a bowl, combine chicken and marinade. Marinate in refrigerator for about 1 hour. Drain chicken from marinade, discarding liquid.

On lightly oiled grates over medium hot coals, grill chicken for about 4 to 5 minutes on each side or until chicken is cooked and juices run clear.

In a bowl, combine sour cream and ranch dressing mix. Stir until blended.

On a baking sheet, arrange chicken on a single layer. Spread top with sour cream mixture and sprinkle with cheese. Repeat with remaining chicken. Bake in a 400 F oven for about 2 to 3 minutes or just until cheese is melted and bubbly. Garnish with pico de gallo, if desired.