To prepare broth, combine first 9 ingredients in a large Dutch oven. Bring to a boil. Reduce heat to low; simmer 20 minutes or until chicken is just cooked through, skimming off and discarding foam as needed. Strain broth through a fine sieve to yield 5 cups (add additional water as needed to measure 5 cups), and discard solids. Remove chicken meat from bones; shred meat. Discard skin and bones.
To prepare porridge, heat oil in a large saucepan over medium heat; swirl to coat. Add sliced white onion; cook 5 minutes or until softened, stirring occasionally. Add rice and next 3 ingredients (through 6 garlic cloves); cook 30 seconds, stirring constantly. Add 5 cups broth and sherry; bring to a boil. Cover and cook 35 minutes or until thick and rice begins to break down, stirring occasionally. (Mixture should be the consistency of rice pudding). Stir in chicken and fish sauce; cook for 2 minutes or until thoroughly heated. Spoon about 1 cup porridge into each of 6 bowls. Top each serving with 2 tablespoons cilantro, 2 tablespoons green onions, and 2 egg halves.