Onions peel, halve and in fine columns cut. Cut bacon and cucumbers into sticks. Place roulades side by side on a large board, spread a thin layer of mustard, season with salt and pepper
Spread the bacon, onions and gherkins on one end of the roulades, fold in the long side slightly if necessary and roll the meat tightly. Stick together with roulade needles. Clean the mushrooms, wash and halve them if necessary
Heat the oil in a casserole or roasting pan. Fry the roulades in it thoroughly all around. Take out, add another 2 tablespoons of oil, heat up, add mushrooms and fry vigorously while turning. Season with salt and pepper. Deglaze with 250 ml stock, bring to the boil and simmer for about 10 minutes
Add roulades again. Add 1 litre of stock and 250 ml red wine, bring to the boil, cover and simmer over a low to medium heat for about 2 hours.
In the meantime clean and wash the Brussels sprouts. Peel and wash the potatoes and cook in boiling salted water for about 25 minutes. Cook the sprouts in boiling salted water for about 18 minutes. Heat milk and butter in a small pot
In the meantime, stir the starch and 4 tablespoons of water until smooth. Lift the roulades out of the stock. Stir the starch into the boiling stock, bring to the boil and simmer for about 1 minute. Season with salt, pepper and icing sugar, add the roulades again, heat up and keep warm
Drain the potatoes, add the hot milk-butter mixture and mash with a potato masher. Season with nutmeg. Pour the Brussels sprouts into a sieve, drain. Arrange roulades with sauce and mushrooms, Brussels sprouts and mashed potatoes on plates