If you have a sandwich it is rather likely to be wrong - unless you make it out of low carb foods of course.
It has taken two years of low carbing to reach a situation where I can eat small amounts of bread with lots of low carb ingredients, 'normal' breads are far too high carb for me and I often eat lettuce roll ups rather than bread sandwiches - a couple of lettuce leaves interlocked, ham or corned beef, sometimes tuna laid on them, usually sliced tomato, maybe pickle or coleslaw, sometimes grated cheese, roll and eat. That is just a list of choices, I don't put all those into one sandwich.