In a large mixing bowl, combine the all-purpose flour, cornstarch, baking powder, salt, black pepper, paprika, and cayenne pepper. Mix well.

Gradually pour in cold sparkling water, whisking until you achieve a smooth batter. A few lumps are fine; avoid over-mixing.

Heat 2-3 inches of vegetable oil in a heavy-bottomed pot or deep fryer over medium-high heat until it reaches 350°F (175°C).

Stir the minced garlic into the batter, being careful not to break the garlic pieces too much.

Dip each halved mushroom into the batter, ensuring they are fully coated.

Carefully drop the coated mushrooms into the hot oil, frying them in batches to prevent overcrowding. Fry for 3-5 minutes, turning occasionally until they are golden and crispy.

Use a slotted spoon to remove the fried mushrooms from the oil, placing them on a paper towel-lined plate to drain excess oil.

Repeat the frying process until all mushrooms are cooked.

Serve the crispy garlic fried mushrooms hot, garnished with chopped parsley and lemon wedges for squeezing over.