Take the beef roulades out of the packaging, wash them and pat dry well with a paper towel. Chop the onions and cucumbers into small pieces. Wash the soup greens, peel and cut into small pieces and set aside. Spread a thin layer of mustard on the spread out roulades and season with salt and pepper.
Then spread the onion and cucumber pieces as well as the bacon over the entire roulade. Fold the outsides into the roulade and carefully roll up from top to bottom. Insert a roulade needle into the end of the roulade so that it stays together. Preheat the oven to 200 degrees / top and bottom heat.
Let the clarified butter heat up in a large cast iron roaster and fry the roulades all over. When the roulades are seared on all sides, add approx. 200 ml of water, put the lid on and place the roulades in the preheated oven. After about 30 minutes, look at the roulades and turn them over and add the soup greens (do not place on the roulades).
The roulades take two hours in total. It is best to check the roulades every 30 minutes, add water if necessary and turn the roulades again after an hour. After two hours, prick the roulades with a knife and see if they are soft. Take out the roulades, remove the needles from the roulades and keep the roulades warm.
Pass the stock of the roulades through a sieve and pour into a small saucepan. Mix a glass with approx. 200 ml of cold water and 2 tablespoons of flour and whisk well with a whisk until the flour can no longer be seen. Add the water-flour mixture to the sauce and carefully bring to the boil. Add a mug of cream, salt, pepper and a bay leaf and simmer everything together for about 5 minutes. If the sauce is too runny, more flour can be added. Remove the bay leaf and pour the finished sauce back into the roaster. Place the roulades in the sauce and keep warm until you eat them.