Cut carrots and onion into thin slices. Season meat with salt and pepper, spread with mustard. Put 2/3 of the onion and the cucumber on top, roll up and pin. Fry in 1 tablespoon of oil. Fry the rest of the onion and season. Deglaze with broth. Cover and stew for 10-15 minutes.
Cut the potatoes into slices. Fry in remaining oil in a 2nd frying pan for about 10 minutes while turning. Steam carrots and peas in little boiling salted water covered about 2 minutes. Cut parsley into fine strips except for a little bit for garnishing. Drain the vegetables. Melt the fat in the pot. Swivel vegetables and parsley in it
Remove the roulades from the stock. Mix the binding agent in sour cream, thicken the stock with it, season. Arrange the roulades with vegetables, potatoes and sauce. Serve garnished with parsley