Arrange black salt or rock salt on a serving platter and top with cleaned oyster shells.

Prepare the tempura batter: Lightly whisk the egg white until foamy.

Add all-purpose flour and champagne to the egg white.

Add a handful of ice cubes to the batter.

Gently whisk until almost smooth and set aside to rest.

Make the wasabi dressing: Whisk together wasabi paste, grated palm sugar, fish sauce, lime juice, and 1 teaspoon of water.

Spoon a little wasabi sauce onto each oyster.

Heat vegetable oil in a deep fryer or large pot over high heat.

Dry the shucked oysters on paper towels.

Lightly dust each oyster with cornstarch.

Dip the dusted oysters in the prepared tempura batter.

Carefully lower the battered oysters into the hot oil.

Fry for approximately 2 minutes, or until crisp and golden.

Remove the fried oysters and drain on paper towels.

Place each tempura oyster back into its shell.

Top each oyster with finely sliced spring onions.

Serve immediately with the remaining wasabi dipping sauce.