Peel, wash and roughly dice the carrot. Peel onions. Chop 2 roughly, cut 2 into fine rings. Quarter cucumbers lengthwise. Dab the roulades dry, possibly tap them a little bit flatter. Season with salt and pepper, spread with mustard.
With 1-2 slices of bacon, 2 cucumber quarters and some onion rings, so that a small edge remains free. Roll up from the narrow side. Pin or wrap around.
Heat clarified butter in a large frying pan. Fry the roulades in it thoroughly all around, take them out. Fry the carrot and onion cubes in the frying fat. Briefly sauté the tomato paste. Deglaze with about 3/4 l water and bring to the boil.
Put the roulades back into the roaster, cover and stew for 1 1/2-2 hours.
Keep the roulades warm. Pour the stock through a sieve into a pot. Stir flour and 4 tablespoons of cold water until smooth. Stir into the stock, bring to the boil and simmer for about 5 minutes. Season to taste. Arrange roulades in the sauce.
Green beans and boiled potatoes taste good with it. Drink tip: strong red wine, e.g. Pinot Noir.