Clean, wash and cut the spring onions into rings. Clean, peel and slice the tubs. Dill wash, shake dry and cut finely. Mix dill and mustard. ##Wash fish, dab dry, cut into 8 slices and season on both sides with salt and pepper.
Place on a baking tray lined with baking paper. Brush the top with mustard-dill mixture. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 12-14 minutes. In the meantime heat up oil in a pan.
Add Mairübchen and stew for about 5 minutes, turning. Add spring onions and stew for another 2-3 minutes. Season to taste with salt, pepper and sugar. Take the fish out of the oven. Arrange vegetables and 2 fish slices on plates.
Garnish with lemon slices and lemon balm. Herb butter ###baguette## tastes good with it.