Wash the roulades, dab dry, tap flatter. Clean and wash spring onions, cut them into pieces of about 6 cm length. Spread the roulades with horseradish. Season with salt and pepper.
Spread the bacon and spring onions over it. Roll up firmly and pin with roulade needles. Heat the lard in a roaster. Fry the roulades in it all around. Peel and chop the onions and fry them briefly.
Deglaze with 1/2 litre water. Cover and stew for about 45 minutes. In the meantime boil 500 ml water. Remove the pot from the heat. Stir in puree powder. Pour the puree into a piping bag with a star-shaped spout.
Spray onto a baking tray lined with baking paper. Just before serving, bake in a preheated oven (electric: 225 °C/ gas: level 4) for 5-8 minutes. Peel and wash the carrots and cut them in half lengthwise.
Cook for about 15 minutes in boiling salted water, then drain. After 45 minutes, deglaze roulades again with 1/4 litre of water, stir in mustard and braise for another 30 minutes. Wash parsley and cut into fine strips.
Melt the fat just before serving. Toss carrots and parsley in it. Refine sauce with cream. Sprinkle with sauce thickener. Season to taste with salt and pepper. Arrange roulades and sauce, carrots and sprinkled potatoes in portions.
Serve garnished with parsley.