Thai Southern Curry with Pork Ribs

1 whole rack St. Louis-cut pork ribs (about 2 pounds; 900g), cut in half lengthwise (see notes)
3 tablespoons (45ml) vegetable oil
4 ounces (1/2 cup; 115g) Southern Thai curry paste
3 tablespoons (45ml) fish sauce
1 tablespoon (10g) coarsely ground black pepper
1 tablespoon (15g) sugar
10 fresh or frozen makrut lime leaves (see notes)
Kosher salt
Cooked jasmine rice, for serving

Pat ribs dry with paper towels. Using a sharp knife, divide into single-rib pieces by cutting through meat between rib bones. Set aside.
In a small or medium Dutch oven, heat oil over medium heat until shimmering. Add curry paste, stir vigorously with a rubber spatula to incorporate with oil, and cook, stirring constantly, until fragrant, about 2 minutes.
Add pork ribs and 1 tablespoon (15ml) water to help loosen paste and stir to evenly coat ribs with curry paste mixture. Cook, stirring and turning ribs frequently, until meat turns pale grey and no longer looks raw on surface but is not browned, 3 to 5 minutes.
Add fish sauce, black pepper, sugar, and 6 cups (1.5L) water. Stir to combine, bring to a rapid simmer, and cook, stirring occasionally, until pork is barely tender and liquid is reduced and thickened, about 1 hour.
Add makrut lime leaves and more water as needed to keep ribs barely submerged (about 1 ½ cups; 375ml), and continue to cook, adjusting heat as needed to maintain a steady simmer, until pork is completely tender and the curry is reduced to a thick, saucy consistency and fat just begins to separate around the edges of the pot, about 30 minutes longer.
Remove from heat, season with salt to taste, and transfer curry to a large serving bowl or divide between individual serving bowls. Serve with cooked jasmine rice.