Peel and finely chop the onion. Knead with mixed mince, 1 egg, breadcrumbs and mustard. Season with salt and pepper. Form 4 large meatballs from the minced meat mixture.
Fry the meatballs in 2 tbsp. oil for about 10 minutes, keep warm.
Peel the pineapple and cut into 8 slices. Peel onions, cut into thick rings. Heat 1 tablespoon of oil in a frying pan. Brown the onions in it, take them out. Heat 1 tbsp. oil in the frying fat. Fry the pineapple in it. Sprinkle 1 tbsp. sugar over it, caramelise slightly. Deglaze with Teriyaki sauce, bring to the boil and boil down a little.
Sort the arugula, wash and drain. Arrange the meatballs with pineapple with sauce, onions and rocket.