1. Put the tuna into a bowl.
2. Add about one or more tablespoons of mayonnaise depending on taste.
3. Add chopped onion and Carrot
4. Place lettucce and tomato slices on one of the bread slices.
5. Spread the tuna mixture on top.
6. Close the sandwich by adding the other bread slice on top of everything
7. Slice in half and serve.