Brush and rinse the potatoes. Leave a little green on some small carrots. Cut remaining carrots into fine strips (julienne). Peel and chop onion. Clean and rinse spring onions, cut lengthwise. Blanch in boiling salted water for about 2 minutes. Remove individual leaves.
Rinse fish fillets, dry, sprinkle with juice of one lemon and season with salt. Place spring onion strips on top, roll up, pin with wooden skewers. Cook potatoes in boiling salted water for about 15 minutes. Cook whole carrots for about 15 minutes, carrot strips for about 7 minutes. Then drain. Melt the fat, saffron in it, toss drained carrot vegetables in the fat.
Heat oil, fry onion briefly in it, add plaice rolls. Extinguish with wine and 1/2 liter of water. Season with salt and pepper. Bring to a boil and simmer on lowest heat with lid closed for about 10 min. Rinse chervil, shake dry and pluck off leaves. Arrange the fish rolls on the saffron, sprinkle with chervil and bring to the table.
Our tip: Use young, tender carrots!