Thinly slice the cabbage and carrot, and slice the cucumber diagonally. You can skip the cucumber if preferred.

In a bowl, mix cabbage and carrot with sugar, vinegar, and salt. Let it marinate for about 10 minutes.

Remove excess moisture from the cabbage mixture and mix it with mayonnaise and mustard.

Cut the morning bread in half like a hotdog bun.

Place cucumber slices inside the bread and fill it generously with the vegetable mixture.