Cut the plaice fillet into strips approx. 4 cm wide and place in a pan with the spring onions and white wine. Sprinkle with salt and pepper. Bring to the boil and simmer for 4 minutes. Then carefully lift the fish onto a warmed serving platter. Cover and keep warm.
Mix the cornstarch with milk and add to the pan with the dill and double crème. Cook for about 2 minutes, stirring, until the sauce thickens slightly. Add grapes and lemon juice and heat for 1 - 2 minutes. Pour over the plaice fillets and garnish with dill.
This goes well with rice and zucchini strips steamed in butter.