Clean, wash and quarter the savoy cabbage and remove the stalk. Cut the savoy cabbage into fine strips
Wash the fillet, dab dry and season. Fold the thin end down. Wrap the fillet with bacon. Heat 1 tablespoon of oil in a frying pan. Fry the fillet for a good 5 minutes on all sides. Take out and let cool down
Peel and chop the onions. Heat 1 tablespoon of oil in the frying fat. Fry 2 tbsp. diced onions and about 1/4 cabbage covered in it for about 8 minutes. Season to taste with salt and pepper. Take out, drain and let cool down
Unroll the puff pastry together with the baking paper on the baking tray. For decoration, cut off an approx. 5 cm wide strip on the short side and chill. Sprinkle breadcrumbs on the pastry sheet. Spread the cooled savoy cabbage in the middle. Place the fillet on top and roll up in the dough. Separate the egg. Spread the edges of the dough with egg white and press down
Cut the rest of the dough into strips and stick them on as decoration with egg white. Brush everything with whisked egg yolk. Place a cup of cold water on the baking tray. Bake in the preheated oven (electric oven: 200 °C/circulating air: 175 °C/gas: level 3) for approx. 25 minutes until golden brown
Fry the rest of the cabbage in 1-2 tablespoons of hot oil. Deglaze with 3/8 l water and cream. Stir in broth and bring to the boil. Cover and stew for 15-20 minutes. Bind with sauce thickener, season to taste. Serve and garnish. Goes well with boiled potatoes