In a medium bowl dissolve 1 ½ teaspoon of cornstarch in the cooking sherry. Add the shrimp to the bowl and toss to coat.
Heat oil in a wok or large skillet over medium-high heat. Add the shrimp and stir-fry until pink (about 3-5 minutes). Remove the shrimp to a plate with a slotted spoon (try and leave as much oil in the pan as possible). Add the garlic and stir-fry for a few seconds, and add the ground pork. Stir-fry the pork while breaking it up into small chunks with a spatula or spoon until the pork is no longer pink.
Combine 1 cup of water, soy sauce, sugar, and salt. Stir into the wok with the pork. Bring to a boil. Reduce heat to medium and cover. Simmer for about 2 minutes. Mix the remaining 1 ½ tablespoons of cornstarch with a ¼ cup of cold water. Pour the cornstarch mixture into the pan with the pork and return the shrimp to the pan. Return to a simmer and stir quickly while drizzling in the beaten egg.