Heat 3 tablespoons vegetable oil in a wok or large saucepan over medium heat. Add onion and garlic; cook and stir until softened, about 5 minutes. Stir in ground chicken; cook until no longer pink, about 5 minutes. Drain grease thoroughly. Stir in oyster sauce.
Reduce heat to low. Mix cabbage, bean sprouts, and carrots into the chicken mixture. Season with salt and pepper.
Place 1 spoonful of chicken mixture in the center of 1 spring roll wrapper. Keep remaining wrappers covered. Fold in opposing edges and roll up wrapper. Transfer to a plate. Repeat with remaining chicken mixture and spring roll wrappers.
Heat 2 cups oil in a wok or large saucepan over medium heat. Fry spring rolls in batches until golden brown, 2 to 3 minutes per batch.
Substitute ground pork for the chicken if preferred.
We have determined the nutritional value of oil for frying based on a retention value of 10% after cooking. Amount will vary depending on cooking time and temperature, ingredient density, and specific type of oil used.