If you have a whole salmon filet, cut it into smaller pieces.
Place the salmon filets in a bowl or oblong dish and cover them with milk.
Soak the fish for 30 minutes to remove any fishy odor or taste. Drain and rinse well.
Tear off a large square of aluminum foil and lay it flat on a surface. Fold the right and left sides of the foil a couple of inches. Then, fold a portion of the bottom and top and crease down, leaving about 6-7 inches to form a gusset in the middle. Lay the foil back down flat. Repeat with three more packets
Lay one salmon filet in the center of the aluminum foil in the gusset area. Repeat with the other salmon filets.
Divide the peppers, garlic and asparagus spears between the salmon.
Add the lemon pepper, parsley, dill, lemon zest, salt and pepper. Top with one tablespoon of butter on each salmon filet.
To form the packet, fold the top and bottom of the foil up to meet above the filets.
Fold down the two ends together several times to seal the top. You may have to squeeze the side together to properly seal the packet, so they do not leak.
Place all the packets on a baking sheet.
Bake in a 350-degree oven for 20 minutes.
Unroll the top of the packets to serve. Leave the fish and vegetables in the packet or take them out.