Korean Beef Lettuce Wraps

head lettuce ((Bibb, Boston, and butter are great choices))

lean ground beef

brown sugar ((or less to decrease sweetness))

soy sauce or tamari

sesame oil; divided in half

garlic; minced/grated

. ground ginger

. red pepper flakes ((optional and to taste))

bunch green onions; divided between white and green parts

rice wine vinegar

Sesame seeds for garnish ((optional))