Pat the shrimp dry with paper towels, then transfer to a medium bowl and season with salt and pepper.
2. Step
In a separate medium bowl, whisk the eggs and soda water until combined. Add the cake flour and gently whisk, making sure the batter is still clumpy. Do not overmix.
3. Step
Heat the oil in a large pot until it reaches 350˚F (180˚C).
4. Step
Add the panko bread crumbs to a shallow bowl.
5. Step
Using a slotted spoon, dip the shrimp in the tempura batter, then toss in the panko, making sure to fully coat.
6. Step
Fry the shrimp in the hot oil, 5-6 at a time, until golden brown, about 2-3 minutes. Transfer to a wire rack to drain.
7. Step
Make the glaze: Heat the oil in a medium saucepan over medium-high heat. Add the garlic and ginger and cook until fragrant, about 30 seconds, stirring frequently.
8. Step
Add the soy sauce, rice wine vinegar, brown sugar, and red pepper flakes. Stir until the mixture begins to simmer.
9. Step
In a small bowl, combine the water and cornstarch. Add the cornstarch slurry to the saucepan and stir to combine. Cook until the glaze is reduced by half and looks thick and syrupy, about 5 minutes.
10. Step
Transfer the shrimp to a large bowl and pour the glaze over. Toss the shrimp gently to coat with the glaze.
11. Step
Serve the shrimp over rice and garnish with scallions.
