In a large bowl, whisk together egg and milk. Add bread, coat it in the egg mixture, and let sit for 10 minutes.
Add ground beef, shallot, garlic, black pepper, salt, and cayenne pepper. Mix well with a wooden spoon or your hands. Shape into small meatballs about 1 to 1 1/4-inch across.
Add Vegetable oil to a large nonstick skillet and heat over medium heat. Working in 2 batches, add meatballs and cook until brown on all sides and no longer pink inside, about 6 minutes per batch. Transfer meatballs to a plate and keep warm. Drain fat from skillet and wipe clean.
In a medium bowl combine apple juice, soy sauce, brown sugar, cornstarch, ginger, and cayenne. Place mixture in the wiped clean skillet over medium heat and stir until thickened and bubbly. Cook 2 more minutes while stirring.
Place meatballs back in skillet and coat with glaze. To serve, sprinkle with green onions and serve over rice if desired.