You can make this tasty dish with your own freshly-caught fish (depending if you have a fisherman in your crowd) or store-bought fresh fish. Most any fish will work, but Michigan Whitefish is divine! 
 

Place fillets of fish on individual pieces of heavy-duty foil (or on two thicknesses of regular foil) - large enough to make into a packet. Top each fillet with thinly cut onion slices and thinly cut lemon slices. Season with garlic salt, pepper, 1 Tbsp. butter, and 1 tsp. of white wine. (Optionally add ½ Tbsp. fresh thyme or parsley). 
 

Wrap packets up, folding seams under to seal. Place the foil packages on the grill above the heat. Turn occasionally with tongs to cook evenly. Cook 30 min. or more, depending on the thickness of the fish (or until the fish is flakey). Serve it right in the foil packets!