Mix all marinade ingredients together and marinade steak for 2-12 hours.
Remove the husk from the tomatillos and drizzle with olive oil. Place under the broiler for 3-5 minutes.
Add all salsa ingredients in a blender and mix until smooth.
Preheat grill for high heat grilling. While warming up, add lime juice and fajita seasoning to a bowl with the shrimp.
After 20 minutes, skewer the shrimp to be grilled.
Grill skirt steak for 3-5 minutes per side or until desired doneness is reached. Remove and grill shrimp for 2-3 minutes per side.
Slice steak into bite sized pieces and remove shrimp from skewers.
Assemble the quesadillas with cheese, salsa verde, steak, and shrimp. Butter a grill top or skillet and add the quesadilla. Cook for 2-3 minutes per side.