In a bowl, combine all the ingredients for the meatballs: ground beef, egg, minced garlic, soy sauce, breadcrumbs, salt, and pepper. Roll the mixture into small meatballs.

Heat some oil in a large pan or wok over medium heat. Fry the meatballs until golden brown and cooked through. Remove them from the pan and set them aside.

Heat extra oil in a pan or the same wok over medium heat. Add the finely chopped garlic and fry for about two minutes.

Add the leek, spring onion, mushrooms, and red bell pepper. Fry for about five minutes.

Then, add the soy sauce, oyster sauce, light brown sugar, and lemon juice. Mix everything together.

Add the bean sprouts and cook for a few more minutes. Mix everything together well.

Season the dish with salt and pepper. Let it simmer for a few more minutes.