In a large heavy-bottomed saucepan, pour enough oil to fill the pan about a third of the way. Heat over medium heat until a deep-frying thermometer inserted in the oil reaches 350 degrees F.
Blend the flour, cornstarch, sesame seeds, salt, sugar, baking powder, water, sake, chile sauce, and fish sauce together in a large bowl. Dip the shrimp and scallops in the batter, letting the excess batter drip back into the bowl and gently drop into the hot oil. Fry the shrimp and scallops until crisp and golden, about 4 to 5 minutes.
To make the cucumber salad: Whisk together the ginger, sugar, chile flakes, rice vinegar, and fish sauce. Toss the cucumber in the dressing and divide between 2 plates.
Remove the shrimp and scallops from the oil and drain on paper towels, season with salt. Place 2 shrimp and 1 scallop on each plate on top of the cucumber salad.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.