Preheat oven to 425ºF (220ºC). Line a baking sheet with foil and lightly spray with vegetable oil.
Method for making the sauce
In a medium sized bowl, combine the coconut milk, stock, lemon juice, hoisin, sugar, cornstarch, ginger, garlic and Sriracha. Stir until the cornstarch is dissolved. Set aside.
Preparing the Meatballs
In a large bowl, combine the beef, egg, hoisin, onions, breadcrumbs, cilantro, garlic, ginger, and salt and pepper. Using your hands, form about thirty 1-inch (2.5 cm) meatballs. Place on the prepared baking sheet and bake in the preheated oven for 10 minutes or until internal temperature reaches 165º (74ºC) when tested with a cooking thermometer.
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 instructions. Drain well.
Top each lettuce leaf with an equal amount of the cooked noodles. Place meatball on top of the noodles and drizzle with the sauce. Garnish with red pepper, sesame seeds and peanuts.