In a bowl, combine food coloring with a few drops of water. Add coconut and cover the container, shake until coconut is tinted. Set aside.
Place 1/2 of the vanilla wafers, flat side up, in an ungreased cookie sheet. Top each wafer with a peppermint patty. Place in the oven about 1 minute or just until chocolate begins to soften.
Remove cookies from oven and sprinkle each mint with 1/2 teaspoon coconut (for lettuce). Place another vanilla wafer on top and press gentle. With a clean paint brush, brush the top of each hamburger with just enough water to moisten so that the sesame seeds will stick when sprinkled on top of each cookie. NOTE: You can use canned chocolate frosting in place of peppermint patty, then eliminate the baking.