Sandwiches as invented by the Earl of Sandwich are distinctly modern not because "using bread to hold your food" is a new idea (that's almost as old as "bread") but because cold cuts are a relatively modern idea since without refrigeration (or at least an ice box with imported ice) cold cuts become lukewarm cuts which you really shouldn't eat.I'd definitely have sandwiches in my games if I was a DM. It's not a question of if they could be made, of course they could. The real question is what the foods in your game can tell you about the cultures that they come from. It's a world building tool. Sandwiches have probably existed as long as bread has, they just never caught on as a big cultural thing. From what I've seen of the culinary past, for the most part small pies took the place of an all-in-one food delivery vehicle. It makes sense for the time and place, most meats availible were lesser cuts and often pushing their shelf life, so a stew would soften the meat and allow seasoning to make them better tasting. Cook that into a sealed hand pie and you've got the perfect quick food. So having a society that favors a sandwich would say something about what that society is. I haven't spent much time thinking about it, so I don't have any solid ideas or examples, but it would be interesting.
Sandwiches as invented by the Earl of Sandwich are distinctly modern not because "using bread to hold your food" is a new idea (that's almost as old as "bread") but because cold cuts are a relatively modern idea since without refrigeration (or at least an ice box with imported ice) cold cuts become lukewarm cuts which you really shouldn't eat.
Also I have to question the whole idea that a sandwich can only be with cold cuts of meat. It might be slightly less common because of the various ways to totally wrap the bread around the filling like a burritos or even tacos makes it a little more portable but only a little.You ever hear of salami? Pickled pork? corned beef? Brawn? A variety of preserved meats were eaten cold. Corned beef preserved in its own fat is a great sandwich topping