Season pork slices with salt and pepper, then shape into 3cm diameter meatballs. Coat lightly with flour.

Cut the onion into 6 wedges (radial slices).

Halve the bell peppers, remove seeds and stems, and slice into bite-sized pieces.

Mix ketchup and Worcestershire sauce in a bowl to prepare the sauce.

Heat salad oil in a frying pan over medium heat. Add onion and bell peppers, stir-fry until softened, then remove from the pan.

Using the same pan, add the pork meatballs and cook over medium heat, turning occasionally until browned and cooked through.