Heat oil in a deep-fryer or large saucepan to 350 degrees F (175 degrees C).
Whisk flour, wine, water, parsley, garlic, salt, and pepper together in a bowl until well combined and no lumps remain. Dip mushrooms, one at a time, into batter to coat.
Carefully place coated mushrooms into hot oil, making sure they don't touch or stick together while cooking; fry until golden brown, 5 to 6 minutes. Drain on a paper towel-lined plate lined. Sprinkle with Parmesan cheese to serve.