Heat oil in a deep-fryer or large saucepan to 350 degrees F (175 degrees C).
Whisk the wine, water, flour, parsley, garlic, salt, and pepper together in a bowl until well combined and no lumps are visible. Dip each mushroom individually into the mixture to coat. Carefully put the coated mushrooms into the hot oil, keeping the mushrooms from touching and sticking together while cooking. Cook until golden brown, 5 to 6 minutes. Remove from oil and drain on a plate lined with paper towels. Sprinkle with the Parmesan cheese to serve.