Wash the meat, dab dry. Heat oil in a pan, fry meat all around, season with salt and pepper and remove. Clean, peel and wash kohlrabi and carrots.
Slice into thin slices. Mix flour with sour cream and cream, season with salt and nutmeg. Grease a gratin dish (26 cm Ø). Place kohlrabi and carrots fan-shaped on the rim. Cut the fillet open and spread it in the middle.
Pour sour cream over it. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 30-40 minutes. Melt the butter in a pan and roast the breadcrumbs in it until golden brown. Remove from heat.
Wash the basil, dab dry and put something aside for garnishing. Cut the rest into fine strips and mix into the crumbs. Sprinkle over the gratin 10 minutes before the end of the cooking time. Garnish with basil.