It isn't uncommon for campfires to be prohibited in protected wilderness areas or areas prone to (or impacted by) wildfire. And even in campsites where controlled campfires are permitted, this hack is a useful one to remember in helping abide with leave no trace principles. So if you're backpacking to a place where the fish are jumpin' (and where you're allowed to catch em!) put last night's Mountain House pouch to re-use by using it as a cooking vessel! Just add boiling water, fresh fish, and a few minutes later the meat will be falling off the bone and ready to eat!