Wash the pork tenderloin and pat dry. Heat the oil. Brown the fillet all around in it until golden brown. Fry over medium heat for another 12-15 minutes. Season with salt and pepper and remove. Deglaze the meat with approx. 200 ml water, put aside
Peel the carrots, leaving a little bit of green, wash them and cut them in half crosswise. Peel and wash kohlrabi and cut into slices. Clean and quarter the pointed cabbage and cut out the stalk. Cut the pointed cabbage into slices as well
Put the carrots and kohlrabi in a wide pot and cook them in about 1/2 litre of boiling salted water for about 12 minutes. Add the pointed cabbage after about 5 minutes and cook. Drain the vegetables well and collect the vegetable stock
Heat the fat. Sauté the flour in it until golden brown. Add the gravy, vegetable stock and cream, stirring constantly. Bring to the boil and simmer for about 5 minutes. Season to taste with salt, pepper and lemon juice
Cut the fillet into slices. Arrange vegetables and meat in a flat casserole dish (approx. 27.5 x 33.5 cm). Pour lemon béchamel over it. Bake in a preheated oven (electric: 200 °C/ gas: level 3) for approx. 20 minutes. Garnish with chervil, basil, lemon balm and lemon slice if desired.