Keep the iceberg lettuce leaves in iced water. Heat oil in a non-stick pan, add garlic and onion and cook till onion turns soft and translucent. Add chicken mince and cook on high heat stirring continuously for about three to four minutes.
Stir in black bean sauce, salt, sugar and crushed black pepper. Mix well. Cook covered on low heat till chicken mince is fully cooked. Remove from heat. Add roasted melon seeds and mix well.
Remove the lettuce leaves from iced water, shake off excess water. Arrange on a serving dish. Put two spoonful cooked chicken mince on each lettuce leaf and lightly roll and secure with a wooden toothpick.