Combine tequila, lemon juice, ground cumin, crushed red pepper, and chopped jalapeño in a zip-top plastic bag. Add pork tenderloin to bag; seal. Marinate in refrigerator 2 hours. Boil tomatillos for 2 minutes; drain. Place tomatillos, lime juice, 1/4 teaspoon salt, cilantro sprigs, avocados, and garlic in a food processor; process until smooth. Preheat grill to medium-high. Remove pork from bag. Sprinkle pork with 1/4 teaspoon salt. Place pork on a grill rack coated with cooking spray; grill 8 minutes. Turn; grill 7 minutes or until a thermometer registers 145°. Let stand 5 minutes; slice. Serve with guacamole.