Heat hot dog 1 minute in microwave and slice thinly lengthwise. Lay slice of Mozzarella cheese on 1 1/2 of open hamburger bun. Lay slices of hot dog on cheese. Put "sandwich" bun together. Wrap in damp paper and melt in microwave for 20 to 30 seconds on medium or until cheese melts. (But do not heat so long that bread gets rubbery). Can also be made in toaster oven with sandwich toasted "open."