Spread butter on both sides of the bread slices and keep them aside.

Then, chop the cabbage, onion, and carrot(julienne) and set aside for later use.

Combine the egg, cabbage, carrots, and onion in a jug/mixing bowl. Add salt and pepper and mix everything well.

Heat a skillet or nonstick pan over medium heat. Add 1 tablespoon of butter to the pan, then pour in the egg mixture, trying to give it a rectangular shape.

Cook until the bottom is fully cooked, about 2 to 3 minutes. Then, cut the omelet in half and flip it over.

Cook the other sides well, about 2 to 3 minutes, or until fully cooked. Take it off the pan when both sides are fully cooked.

Now toast the buttered bread slices on the same pan (about 1-2 minutes on each side or until golden brown)

Once both sides of the bread are golden brown, place the cheese slice and the omelet into one bread slice.

Then sprinkle 1 tsp sugar on top of the omelet and add ketchup and mustard right on top (you can adjust the amount of the sugar, ketchup, and mustard according to your preference).

Cover with another slice of toasted bread. Repeat the same process for the rest of the bread slices.

Slice the sandwich in half and serve it with a glass of fresh juice for a delicious breakfast. Enjoy!