For the garlic sauce, chop the garlic very finely or press through it, mix it with mayonnaise, yoghurt and sour cream until smooth and season the sauce with salt, pepper and lemon juice.
For the beer batter, stir the eggs with the sugar until frothy. Add flour, beer, oil and milk and mix everything into a tough, thick dough. Season to taste with salt, pepper and fondor.
Pull the mushrooms through the batter and fry them in hot oil.