Preheat oven to 450°. Make meatballs: In a large bowl, combine pork, green onion, cilantro, soy sauce, sesame oil, ginger, garlic powder, and egg. Using damp hands, form mixture into 1 ½"meatballs.
Grease a baking sheet with cooking spray and arrange meatballs about an inch apart on tray. Bake until golden and cooked through, about 15 minutes.
Meanwhile, make dipping sauce: In a small bowl, stir together soy sauce, vinegar, sambal olek or chili garlic sauce, sesame oil, and sesame seeds.
Transfer cooked meatballs to a plate and sprinkle with green onion. Serve with dipping sauce, with lettuce leaves on the side if desired.
