Mix together the mustard, tomato paste, soy sauce, salt, pepper and paprika. Spread on the roulades. Spread 2 slices of bacon, a cucumber quarter and onion cubes on each of the meat slices. Roll up and close with roulade needles or twine.
Sear in fat on all sides on high heat. Add the onions and carrots, the seasoning ingredients and the bay leaf. Pour in some liquid and simmer the roulades on medium heat for approx. 70 - 80 minutes. In between, pour in liquid until everything is used up. At the end, take the roulades out of the roaster and keep warm.
Pass the gravy through a sieve. Thicken with the sour cream and mixed starch. Possibly whip with the hand blender. Season again to taste.
We also love apple red cabbage or Leipziger Allerlei and Silesian Klassla.