For the dough, sift 100 g flour. Separate the egg, set aside the egg whites. Stir beer, 1 pinch of salt and egg yolk into the flour with the whisk of the hand mixer and let it swell. Meanwhile clean and wash the leek and cut it into four pieces of about 15 cm long.
Cut the remaining leek into strips. Bring the stock to the boil. Add the tomato paste and lentils and cook covered over a low heat for about 20 minutes. After 15 minutes add the leek strips.
Season with salt and pepper. Meanwhile, for the sauce, melt the fat in a saucepan, dust with the remaining flour and sauté briefly. Deglaze with milk while stirring, bring to the boil. Add cheese and let it melt.
Season to taste with salt and pepper. Heat frying fat to 180°C. Beat the egg white until stiff and fold into the dough. Pull leek sticks through the dough and fry in the fat for approx. 5 minutes. Place the lentils on a plate.
Arrange leek sticks on top and cover lightly with the sauce. Remaining sauce extra is enough.