I was flicking through the US Forest Service's Wilderness Ranger Cookbook yesterday and came across this (quoted verbatim). Not quite a pouch meal but nonetheless, protein and long-lasting. And fast!
"The Eagle Cap Club
Jim Bradley, 10 seasons, Eagle Cap Wilderness
1 dry salami, the hottest and spiciest you can find
1 lb. sharp cheddar cheese
1 box of your favorite crackers
This is my favorite trail lunch. It's fast, easy and tasty. Slice the cheese and salami. Place between two crackers to make a sandwich. The ingredients can easily survive a ten-day hike in the heat. This is named in honour of the Eagle Cap Wilderness where this sandwich has kept me alive for years."
I guess that you could use oatcakes as an alternative to crackers.