Mix the meatballs: Combine 1 pounds ground pork, 0.5 pounds ground beef, 2 shallots, minced, 3 garlic cloves, minced (for meatballs), 2 tablespoons fish sauce (for meatballs), 1 tablespoons brown sugar (for meatballs), and 1 teaspoons black pepper. Mix until tacky, then rest 20 minutes in the fridge so it firms up.
Make the sauce: Dissolve 3 tablespoons sugar (for sauce) in 0.8 cups warm water, then stir in 0.3 cups fish sauce (for sauce), 3 tablespoons lime juice, 2 garlic cloves, minced (for sauce), and 1 Thai chile, sliced. Toss 1 carrot, thinly sliced with 2 tablespoons rice vinegar and a pinch of sugar, then add it to the sauce to lightly pickle.
Cook the rice: Rinse 1.5 cups jasmine rice and cook it with your usual method.
Shape and sear: Roll the mixture into balls about 1.5 inches across. Toss them with 1 tablespoons neutral oil (for meatballs) and broil, grill, or sear them in a hot skillet, turning, until well charred and 160°F inside.
Soak and serve: Drop the hot meatballs into some of the sauce for a minute, the way bún chả is served. Set out rice, 3 heads Belgian endive, leaves separated, 1 cups mint, cilantro, and Thai basil, mixed, and extra sauce for building cups at the table.