Prepare 30 minutes prior to grilling ( can be prepared the day before).
In a bowl, stir to combine tomatillos, onion, jalapeno, garlic and cilantro.
Add lime juice, olive oil and cayenne. Stir to incorporate.
Place ¼ of the verde salsa on top of each filet. Wrap fish and salsa in the foil and pinch tightly to close. Set to the side.