Put black sesame seeds and sugar in a food processor and process until the mixture looks like a black paste.
Add egg white and vanilla extract and mix.
Put the mixture in a plastic zip-lock baggie, cut off a tip of the bag; or put in a pastry bag.
Swirl the mixture out on an ungreased cookie sheet. I like making my cookies 1.5 x 1.5 inches so there are enough swirls, they look snail/turd like. They don't spread so having about an inch apart from the cookies will be fine.
Bake for 11-15 minutes. If you like your cookies softer, leave them in for 11 minutes. Longer will be crispier.