These aromatic Thai ribs employ a unique cooking technique. First, marinate the ribs in a fragrant homemade curry paste; then braise them in a pot sealed with a bowl of ice water, which bastes continuously for a dish that’s tender and flavorful. (Note: Authentic Thai ingredients can be found at most Asian specialty stores.)
Paste: Prepare ingredients to make the paste. Peel and thinly slice galangal and turmeric; thinly slice cilantro roots. Trim lemongrass stems, then discard tough outer layers; slice into thin coins. Slice chiles into ½-inch pieces. Peel garlic cloves, then roughly chop.
Place the mortar and pestle on a towel to keep it sturdy. Chef Ricker advises adding ingredients from hardest to softest texture when making a paste. Place dried chiles into the mortar along with a pinch of salt; pound until chiles are flaky. Add peppercorns and continue pounding, followed by galangal, turmeric, and cilantro root. As the ingredients are added, a rough paste will begin to form. Continue by adding lemongrass, garlic, and green chiles. When all of the ingredients have broken down to a rough pulp, the paste is ready. Makes about ⅓ cup.
Ribs: Place rack meat-side down on a cutting board. Cut into individual ribs and place in a bowl. Stack lime leaves, roll like a cigar, slice very thinly (this is called a chiffonade), and set aside. Season ribs with a pinch of salt, fish sauce, sugar, and MSG (optional); toss to coat with your hands. Add the paste and 1 teaspoon sliced lime leaf, reserving the rest for garnish, and massage the ingredients into the ribs until they’re evenly coated. Let rest uncovered at room temperature, 1 hour.
Add oil to a pot over medium-high heat; when it's smoking, add ribs meat-side down in an even layer. Turn heat to medium-low (to prevent paste from burning) and brown the ribs, 6–8 minutes.
While ribs are browning, add 5 pounds ice cubes to the bowl, along with enough water to cover the ice. When ribs are browned, turn them over and reduce heat to low. Place the bowl with ice slurry on the pot so it completely seals off the top. The steam will rise and condense on the cold surface of the bowl, then drip back onto the ribs, creating a self-basting cooking environment.
Garnish: While ribs are cooking, trim and thinly slice the scallion. Roughly chop cilantro. Fold sawtooth leaves in half and julienne into ⅛-inch slices. Mix together scallion, cilantro, and sawtooth and set aside, along with remaining lime leaf.
After 15 minutes, remove bowl from pot and turn the ribs over. Pour out melted ice slurry and replenish with another 5 lbs ice cubes and water. Add a pinch of salt to the ice water to keep it cold a little longer. Place bowl over pot and continue cooking, 15 more minutes.
After 30 minutes of total cooking, remove the bowl. Continue cooking ribs uncovered to reduce the cooking liquid in the pot, 5 minutes. Taste and adjust seasoning by adding salt, sugar, and fish sauce; remove from heat. Place ribs on a serving platter, and spoon paste from the pot over them. Garnish with chopped herbs (scallions, cilantro, sawtooth) and lime leaves. Serve.