Sort the kale, wash thoroughly and drain. Blanch the kale in portions in boiling water for about 5 minutes. Drain, rinse with cold water, drain and let cool. Coarsely chop the kale. Peel and chop onions. Heat 25 g lard in a pot, fry onions in it. Add kale and pour on approx. 200 ml water. Add mead ends and braise covered for about 45 minutes
Wash potatoes thoroughly and cook in boiling water for about 20 minutes. Drain, rinse with cold water and peel. Season the kale with salt and pepper. Remove the sausage and let it cool down. Cut potatoes and mead into cubes. Let the strudel dough rest at room temperature for 15-20 minutes before processing. Melt 75 g lard in a small pot
Let the kale drip off a little, if necessary, and mix in the potatoes and mead. Spread a damp tea towel on the work surface and place a dry cloth on top. Remove 2 sheets of strudel dough from the package and unfold. Place 1 sheet on the prepared cloths, spread with a little lard, place the 2 sheets on top, turned by 45°. Place the remaining sheets of dough on top as well, always brushing them with a little lard
Sprinkle strudel dough with breadcrumbs. Spread the kale mixture on top, leaving about 2 cm free at the edges. Whip the side ends of the dough a little. Roll up from the bottom side using the cloths. Place diagonally on a baking tray lined with baking paper and spread with the remaining lard. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 30 minutes. Mix sour cream with mustard, season to taste with salt and pepper. Serve with strudel