Sift flour. Add oil and salt. Stir in 150 ml of lukewarm water until the dough is smooth and can be easily "pulled". Form into a ball and brush with oil. Cover and let rest for 30 minutes.
Peel the kohlrabis and cut into sticks. Peel and chop the shallot. Steam both in butter for 8 minutes. Season with salt, pepper and nutmeg. Wash the chives, chop finely and fold in. Pull out the dough very thinly.
Spread with melted butter. Spread kohlrabi on the lower third of the dough. Roll up the strudel and brush with butter. Bake in the preheated oven (electric: 200 °C/ gas: level 3) for about 15 minutes.
Cut mushrooms crosswise. Clean, wash and cut leek and carrot into strips. Fry everything in oil and season with salt. Deglaze with ketjab, soy sauce and stock. Cook vegetables for about 5 minutes.
Stir starch with a little water until smooth. Stir into the sauce and bring to the boil again. Season with Shiishini Toogarashi.