Cut the schnitzel into strips. Peel onion and chop finely. Drain the pineapple in a colander while collecting the juice.
Mix the meat, onion, 2-3 tablespoon pineapple juice and soy sauce. Marinate for approx. 20 to 30 minutes. In the meantime, clean the peppers and cut into fine strips.
Heat the oil in a wok. Remove the meat from the marinade and let it drain. Fry in portions in the hot oil, remove and then season with salt. Put the paprika strips in the roasting fat and sauté briefly. Deglaze with the marinade and the Chinese sauce and cook for approx. 5 minutes.
Add the meat and pineapple pieces to the pepper strips in the wok and heat in it. Season the bell pepper pan with the remaining pineapple juice, salt and sambal oelek.