Clean the mushrooms and cut into small pieces. Peel onion and garlic and chop finely. Heat a pan with a little oil and fry the mushrooms, onions and garlic. Season with salt and soy sauce and deglaze with the milk. Stir in the cheese. Mix the biobin with a little water in a glass, pour over the mushrooms and bring to the boil until the ragout has thickened a little.
Peel and slice the potatoes. Heat some oil in another pan and fry the ham cubes in it, then add the potatoes and fry. Season the potatoes with a little salt.