Heat a large skillet over medium-high heat. Cook and stir ground beef in the hot skillet until browned and crumbly, 5 to 7 minutes. Drain and discard grease. Add onion, garlic, ginger, and 1/2 of each of the following ingredients: soy sauce, sherry, salt, and pepper. Sauté just until onion is tender, 4 to 5 minutes. Transfer to a bowl.

Heat 1 tablespoon oil in the same skillet over medium heat. Add cabbage, water, and sugar, plus remaining soy sauce, sherry, salt, and pepper. Cook and stir until cabbage is crisp-tender, about 5 minutes. Return beef mixture to the pan; cook and stir until well combined and heated through, 2 to 3 minutes. Remove from the heat.

Heat oil in a deep fryer or large saucepan to 350 degrees F (175 degrees C).

While the oil is heating, lay one egg roll wrapper out like a diamond. Place approximately 1/4 cup filling across the center going from left to right. Moisten the top two edges with water. Fold the bottom corner up and over the filling, fold both sides in toward the center, and roll upwards to seal. Repeat to make remaining egg rolls.

Fry a few egg rolls at a time in the preheated oil until golden brown, 2 to 3 minutes per batch. Drain on paper towels and serve hot.