Upvote:1
I used to carry around a dark chocolate bar and a can of tuna in my backpacking days.
Dark chocolate is energy-packed and not sweet, especially if you opt for 80-90% cocoa, although this can be an acquired taste!
Tuna can be eaten on its own in a pinch, but I usually used it for a simple sandwich. As a former French colony, you can get a pretty decent baguette almost anywhere in Laos, and they're quite "trustworthy" too: if it's not visibly moldy, it'll be safe to eat.
Upvote:2
You'll have to make your own sandwiches. Buy pilot bread (a from of hard tack), party bread or Mestemacher bread (comes in many varieties) for your carbs and shelf stable salami and/or pepperoni for your meat. All five are readily available in grocery stores and Amazon.
Make your sandwiches with no other additions or condiments. First wrap them well individually in plastic wrap, then aluminum foil, then place 4 to 6 them in a small ziplock, repeat as needed. Then place all ziplocks into a larger ziplock.
Keep out of direct sunlight.