Step 1Combine the rice vinegar with the sliced chiles and let stand so the chiles become pickled.
Step 2Meanwhile, place the pork on a cutting board. Top with the garlic and the fish sauce. With a Chinese cleaver or other sharp, heavy knife, chop the meat and garlic together until finely minced, almost pasty.
Step 3Place the rice in a large saucepan, add 3 cups of water and cook over low heat until creamy, about 30 to 35 minutes. The rice will soften and break down, like a puree. Keep adding water as needed so that it stays fluid like a soup. Stir in 1 teaspoon of salt. Keep warm over low heat.
Step 4Shape the pork mixture into small patties 2 to 3 inches wide. Heat the oil in a skillet over medium heat. Fry the patties in batches until browned and cooked through, 2 to 3 minutes a side.
Step 5Ladle the rice soup into 4 large soup bowls. Place 3 or 4 pork patties in each bowl. Garnish with cilantro and pepper to taste.
Step 6Serve with fish sauce and vinegar-chile mixture, letting diners season their own soup.