To make the sauce — combine the mayonnaise, chili sauce, honey, salt and 1 tablespoon of water in a large bowl; set aside.
Heat about 2 inches of vegetable oil in a heavy-bottomed pot or Dutch oven over medium heat until a deep-fry thermometer registers 350 degrees. Meanwhile, whisk the eggs in a shallow bowl. Whisk the flour, cornstarch and 1 teaspoon each salt and pepper in another shallow bowl.
Working in batches, dredge the oysters in the flour mixture, shaking off any excess, and dip in the beaten eggs, then return to the flour mixture, turning to form a thick crust. Fry the oysters in the hot oil until lightly golden, 1 to 2 minutes, adjusting the heat as needed to maintain the oil temperature. Transfer to a paper-lined plate with a slotted spoon.
Toss the oysters with the prepared sauce. Arrange on a bed of shredded lettuce and garnish with scallions.