I gill and gut the trout.

For the foil pouch, roll out a piece as long as the trout plus 3 inches. Fold it is half, then fold the sides over .5 inches 3 times. Now you have a rectangle pouch that is as long as the trout. Cut an onion in half and slice in .25 inch sections. Lay the onion in the pouch on one side. Peel a couple cloves of garlic and give them a good wack with the side of a knife, place these in the body cavity of the trout, more or less to taste. Add a good sprinkle of salt and pepper to both sides of the trout and the inside with the garlic. Place the trout on the onion in the pouch and put a fresh herb on the top side of the trout. I like a clump of dill or rosemary, but any fresh herb will do. Now close the pouch with 3 .5 inch folds on the top. Place this whole thing onion side down on a bed of coals for 5-7 minutes, then flip for 2-3 minutes. Cooking time is for a 8-12 inch fish, more for a larger one. Slice open the bag and eat. Don't forget to eat the cheeks, they may be small but Mmmmm.

If you want a stream side lunch, it is easy to carry the pouch with all ingedients in it, add your trout and make a small fire. I supose it would work just as well with 2 fillets, but you can eat one side then lift the whole skeleton out then eat the other side, much easier and faster.