Wash the cucumber and cut into slices. Peel and chop the onion. Mix vinegar, sugar, salt and pepper. Add 1 tablespoon of oil. Wash the dill and pluck into little flags. Mix cucumber, marinade and dill and leave to stand.
Wash the plaice, dab dry and sprinkle with lemon juice. Season with salt and turn in flour. Heat the remaining oil in a frying pan and fry the plaice first, light side down, over low heat for 8-10 minutes on each side.
Dice the bacon. Clean and wash spring onions. Cut dark green into rings. Clean, wash and quarter the tomatoes and remove the seeds. Dice tomato. Leave bacon out in a pot. Brown the spring onions in it.
Wash lemon hot and cut into slices. Add lemon slices and diced tomatoes and sauté briefly. Season with salt and pepper. Pour the vegetables over the plaice and sprinkle with coarse pepper.
Add the cucumber salad.