Preheat oven to 425F. Line a baking sheet with foil and spray lightly with vegetable oil.
Make the sauce: In a bowl, combine coconut milk, stock, lemon juice, hoisin, sugar, cornstarch, ginger, garlic and Sriracha and stir until cornstarch dissolved.
Make the meatballs: In a bowl, combine the beef, egg, hoisin, onions, breadcrumbs, cilantro, garlic and ginger. Using your hands, form about thirty 1-inch meatballs. Place on the prepared baking sheet and bake for 10 minutes.
In a small skillet over medium heat, cook the prepared sauce until slightly thickened, about 2 minutes.
Meanwhile, in a saucepan of boiling water, cook the noodles according to the package directions. Drain well.
Top each lettuce leaf with an equal amount of the cooked noodles. Top noodles with three meatballs and drizzle with sauce. Garnish with red pepper and sesame seeds.