SPREAD 1 bread slice with mustard.
FILL bread slices with remaining ingredients.
How to Slice Tomatoes:
To easily slice a tomato, hold tomato so that the stem end faces out. Cut a thin slice off the stem end with a sharp chef's knife or serrated knife. Discard the trimmed end. Cut the tomato into slices of the desired thickness. Tomatoes cut this way will keep their juice better than those sliced vertically (from top to bottom).