Cook the rice in boiling salted water for 20 minutes. Wash the fish, dab dry and sprinkle with lemon juice. Season with salt and pepper. Turn in breadcrumbs and tap lightly. Heat oil in a pan.
Fry the plaice fillets for 6-8 minutes. In the meantime, clean, wash and chop the spring onions. Drain the pineapple on a sieve, catching the juice. Take the fish out and keep warm.
Sauté spring onions and pineapple pieces in the frying oil. Deglaze with 3-4 tablespoons of pineapple juice and let it boil down a bit. Add sweet-sour Asian sauce and bring to the boil. Season to taste with salt and pepper.
Arrange the fish with the sauce and the rice on a plate.