Gently rinse the zucchini blossoms under cool water if needed and pat dry with paper towels. Open each petal carefully and pinch out the inner pistil, which turns bitter when fried.

In a mixing bowl, stir together the ricotta, egg yolk, parmesan, lemon zest, mint, salt, and pepper until smooth and thick enough to hold its shape on a spoon.

Spoon or pipe about 1 tablespoon of the ricotta mixture into each blossom. Twist the petal tips gently closed to seal the filling inside.

Whisk the flour, cornstarch, and salt together in a bowl. Pour in the ice-cold sparkling water and whisk just until smooth; a few small lumps are fine.

Pour sunflower oil into a 28 cm / 11-inch skillet to a depth of about 2 cm / 3/4 inch and heat to 170C / 340F.

Dip each stuffed blossom into the batter, turning to coat completely, and let the excess drip off for a second before lowering it into the oil.

Fry 4 to 5 blossoms at a time so the oil temperature doesn't drop. Fry for 3 to 4 minutes total, turning once, until the batter is golden and crisp.

Lift out with a slotted spoon onto a paper towel-lined plate and salt immediately while still hot.

Repeat with the remaining blossoms, letting the oil come back to 170C / 340F between batches. Serve right away.