Heat a pan, add the oil, the mushrooms, half of the onion, the entire garlic clove and fry in medium low heat until the mushroom will be thoroughly cooked. Discard the garlic clove. Set aside and cool down.
Add the sour cream and the heavy cream to a bowl and whip until soft peaks will appear.
Chop finely the apple, add it to the bowl together with the sautéed mushrooms and rest of the onion.
Add salt and pepper to taste. Decorate with chives.