Salami
When you get a sandwich in the UK you have quite a range of spreads, but I've never seen salami.
In Germany that was my go to as a kid to have a slice of bread, some butter and a slice of salami, for breakfast, dinner or taking a sandwich to school.
In Germany you can get loads of different kinds of sausage for sandwiches, big slices of sausage, salami, bologna or Teewurst, which is a spreadable sausage and has nothing to do with tea, or Liverwurst.
There isn't that much choice of that kind of stuff in the UK and at first I really missed it.
The weirdest thing to me was the fact that you get German Salami in supermarkets, because I never thought of Salami as being something German. We do have Hungarian, Italian, French and Spanish Salami and if you want more exotic sausages you get Polish, which are delicious as well.
I know that sausage an Germany is a common joke, but I think that only refers to sausage shaped sausages and not presliced or spreadable stuff.