Soak the rice in 400 ml boiling salted water for about 20 minutes. Peel two grapefruits so that the white skin is completely removed. Cut the fillets out of the parting skins, collecting the juice.
Squeeze the rest of the grapefruit. Mix butter, 2 tablespoons grapefruit juice and paprika. Rinse fish cold, dab dry and cut into larger pieces. Season with salt and pepper. Mix flour and thyme, turn fish pieces in it.
Fry in two tablespoons of hot oil on both sides for 3-5 minutes. Clean, wash and chop the spring onions. Fry briefly in the remaining oil. Remove from the pan. Add the grapefruit fillets and juice to the frying fat and let it boil down a little while stirring.
Season to taste with lemon juice, salt, pepper and sugar. Arrange fish pieces with rice, spring onions and sauce on four plates. Put butter in a piping bag with star spout and squirt as a rosette on top of the 2 grapefruit fillets.
Put it on the fish.