Asklemmy

Get some mason jars and do oldschool canning. Food will stay preserved well as there's no bacteria at the temperature you put it in there, and no air will get in.

Toss in some macaroni and pasta sauce, goulash, tomato soup, premade cup-o-noodles with your favourite veg and protein. Your imagination is the limit.

Whenever I go camping I pack a cooler with ice and put my perishable food items in there. Easy to grab snacks, like fruit, pastries, and pre packaged items are also a favourite of mine.

Also, having a portable grill helps when you cannot use fire to cook.

I’d recommend cured meats like smoked sausage or jerky along with crackers. I believe you can do cous cous without boiling the water too but I could be wrong there.

There are also some dehydrated backpacking meals that don’t require boiling the water. Usually they are the breakfast ones with powdered milk and granola and dehydrated fruits - they’re delicious and some of my favorite backpacking food!!

Some boiled eggs are easy

I mean I would just eat cold canned ravioli because that's delicious and it would be a great excuse to eat cold canned ravioli, but you do you

Get bread and canned fish. You can also get canned tomato soup and eat it cold. And then make sure to bring some fruits or something.

Freeze-dried vacuum-packaged hiking food. A bit expensive though.

No easy access to fire? Is that because fire is forbidden or because getting wood and/or a place to burn stuff isn't available? If it's the latter, a gas burner is your friend

Babybel cheese

You can get either canned or dried fruits and veggies that last longer un-refrigerated and have some nutrition to them. Obviously there's power bars as well. Dry cereal if you don't mind eating it dry, makes a decent snack too, or bring powdered milk if you do want to eat it with milk. I've heard freeze dried foods are popular with backpackers. Bananas last long enough if you get them fresh enough. I think there are other fruits and veggies that you don't need to refrigerate for them to last long enough, like tomatoes, cucumbers, oranges, pears, kiwis, apples, etc, just as long as you eat the whole thing in one go cause they don't last as long once they're cut or bit into. Oh and fruit cups are also an option. And of course there's bread, but if you want some variety there you can make/buy some banana bread to take with you as well. Popcorn also lasts quite a while if kept in a sealed bag. You can also eat ichidan or other dry packaged noodles dry, just break them up into smaller pieces in the bag, take out the flavour packet, and either pour the packet into the bag, or pour the noodles and flavouring into a bowl, and mix it up. Tastes pretty good, and makes for a good snack. Not very nutritious, but cheap and easy. There's also pop tarts, which can be eaten cold.

Those are the ones I can think of off the top of my head. You don't need to take all of them for just 4 days, but it's nice to have options.

If you're in England look into the Duke of Edinburgh club. It's an outdoors camping club for youth. You should be able to find a packing list and it will have food suggestions.

That's just long enough for things that aren't shelf stable to start going bad, depending on local conditions. Bread can mold in a couple days though, in warm and humid places.

So, focus in on shelf-stable or preserved things, whether made in a modern method, (sterile packaging of some sort) or an old fashioned method, (drying, curing, smoking) or just naturally able to keep (nuts, seeds, chocolate, honey).

Someone posted their granola bar recipe, that looked pretty solid. I would certainly not bring a bunch of pasties or a calzone unless I was also bringing a cooler. Then I'd be bringing ingredients and tools and making them on-site just for fun, as I assume I'm now car camping, or at least camping fairly close to my vehicle. If backpacking in, then absolutely not. Ready-to-eat, shelf-stable stuff only, to cut weight and stay efficient. And a pasty or calzone would squish in the backpack and end up gross anyway.

Lembas bread

Fruits, rice, pasta

Edit: dont do rice, it’s a bad idea

What I found to be quite interresting and working well are the solid fuel stoves from esbit. You should be able to bring them on a flight and one small tablet lasts long enough to boil enough water for some instant ramen, soup or a cup of instant coffee.

Triscuits.

Ramen and soylent

This website is very helpful and informative https://trailcooking.com/