Liquefy fat and mix with flour and 150 ml lukewarm water. Knead for ten minutes, wrap in plastic wrap and rest for about 30 minutes. In the meantime, cut carrots and spring onions into coarse pieces. Cut German Gouda into strips. Rinse parsley and pluck leaves from stems. Chop the leaves. Separate one egg. Mix minced meat with curd cheese, one egg and one egg white.
Season with salt and pepper.
Grease baking tray. Roll out dough on a large floured tea towel (a kitchen towel is best for this) and, using the backs of your hands, roll out very thinly from the center outward to a rectangle of about 50 x 80 cm. Spread the minced meat mixture on one half of the dough (thin side), sprinkle with cheese, spring onions, carrots and parsley. Using the towel, loosely roll up the dough, wrap the sides and place the strudel on the baking tray. Mix egg yolk with milk and brush the strudel with it.
Bake in a heated oven (electric oven 200 degrees, convection oven 180 degrees, gas mark 3) for about 40 minutes.
Tip: Do you know purple carrots? This is an old, very aromatic variety – why not use it for a change!