Take fresh dough out of the tin according to instructions, unroll and cut into triangles. Spread the triangles with mustard. Halve or quarter the sausages on the broad side of the dough and roll them up. Place on a baking tray lined with baking paper. Bake in a preheated oven (electric cooker: 200 °C/ gas: level 3) for approx. 15 minutes.
Mix egg yolk and cream and brush the croissants with it about 5 minutes before the end of the baking time. Sprinkle with roasted onions and bake. Serve warm garnished with parsley. Served with coleslaw