1. To prepare rice balls, place rice in a sieve. Rinse with cold water; drain. Bring 3 cups water to a boil in a saucepan; add rice to pan. Cover, reduce heat, and simmer 20 minutes or until liquid is absorbed. Remove from heat; let stand, covered, 10 minutes. Place rice in a large bowl; cool to room temperature.
2. Bring the remaining 1 cup water to a boil in a small saucepan; add shrimp to pan. Reduce heat, and simmer for 20 minutes. Drain well; finely chop shrimp.
3. Steam sausage, covered, 15 minutes or until thoroughly heated. Cool slightly; finely chop. Heat 2 teaspoons oil in a medium nonstick skillet over medium heat. Add onions and garlic; cook 1 minute, stirring frequently. Add shrimp, sausage, and bamboo shoots; cook 1 minute. Stir in 1 tablespoon soy sauce, fish sauce, granulated sugar, and pepper. Add remaining 1/2 teaspoon oil, shrimp mixture, and cilantro to rice, stirring gently to combine. Roll rice into 36 (1-inch) balls. Arrange balls in a single layer on a baking sheet; cover and chill 2 hours.
4. To prepare sauce, combine 1/3 cup soy sauce and remaining ingredients in a small bowl; stir with a whisk. Serve rice balls at room temperature with sauce.