Rinse the shrimp under cold water and pat them dry with paper towels. Set aside.

In a mixing bowl, combine the flour, cornstarch, baking powder, salt, and black pepper. Gradually whisk in the water until you form a smooth batter.

Heat the vegetable oil in a deep pan over medium-high heat until it reaches around 350°F.

Dip each shrimp into the batter, allowing excess to drip off. Carefully place the shrimp in the hot oil, frying them in batches to avoid overcrowding. Fry until golden brown, about 3-4 minutes on each side. Remove and drain on a paper towel-lined plate.

In a saucepot, combine the fresh orange juice, orange zest, sugar, soy sauce, and rice vinegar. Bring this mixture to a boil over medium heat.

Once boiling, reduce the heat and allow to simmer for about 5 minutes, stirring occasionally until the sugar dissolves and the sauce thickens slightly.

Stir in the cornstarch slurry to thicken the sauce. Once it reaches the desired thickness, remove it from heat.

Toss the crispy shrimp in the orange sauce until they are evenly coated.

Serve the shrimp hot, garnished with chopped green onions and sesame seeds.