Peel and dice the onions. Clean the mushrooms and cut them into slices.
Heat the oil in a large saucepan and sweat the onions in it. Add the mince and fry until crumbly. Then fry the mushrooms briefly. Season with salt, pepper and the mustard. Deglaze with 1/4 l water and the wine. Bring to the boil and stir in the broth. Let simmer for a few minutes.
Mix the cream and flour until smooth and add. Always stir firmly so that nothing clumps. Let simmer for another 5 minutes.
Cut the cucumbers into sticks and heat them in the minced ragout. Season to taste with salt, pepper and a pinch of sugar. If you want, you can sprinkle with chopped parsley.
Rice or any kind of potato dish tastes good as a side dish.