Soak the stale bun in warm water until softened, then squeeze out excess water. Peel and finely dice the onion.
In a bowl, combine the minced meat, diced onion, squeezed bun, and egg. Mix well with a fork. Season with salt, pepper, and nutmeg.
Heat 100 g of oil in a pan over medium-high heat. Form small balls from the mixture and press them flat. Fry for 10-15 minutes until cooked through. Transfer to a board to cool.
Drain the pineapple well and cut into pieces similar in size to the meatballs.
Wash and dry the grapes.
Place a meatball on each pineapple piece and secure with a toothpick. Thread the grapes onto the toothpick.