Ingredients

• 1 stalk fresh lemongrass, root end trimmed and 1 or 2 outer layers discarded
• 3 (2- to 3-inch) dried hot Thai chiles, including seeds
• 3 tablespoons minced shallot
• 2 tablespoons minced garlic
• 2 tablespoons shrimp powder or 1 1/2 tablespoons dried peeled shrimp (see cooks' note, below)
• 1 teaspoon minced cilantro root or stem
• 1 teaspoon minced Kaffir lime zest or regular lime zest
• 1 teaspoon minced peeled galangal (fresh or thawed frozen)
• 1 teaspoon kosher salt
• 5 black peppercorns
• 1 teaspoon Thai shrimp paste
• 1/2 pound long beans or green beans, cut into 1-inch pieces
• 3/4 pound boneless pork shoulder
• 3 tablespoons peanut or vegetable oil
• 1 tablespoon Asian fish sauce
• 1 tablespoon packed grated palm sugar or light brown sugar
• 3 medium Kaffir lime leaves (fresh or thawed frozen; 2 sections each), ribs discarded and leaves minced
• Equipment: a smooth stone mortar and pestle
• Accompaniment: white rice

Instructions

1. Mince 1 tablespoon lemongrass from root end. Put minced lemongrass and remaining paste ingredients in mortar and vigorously pound to a smooth paste using pestle (most chile seeds should be crushed), 6 to 8 minutes.
2. Cook beans and pork: Cook beans in a medium saucepan of boiling salted water (1 teaspoon salt for 2 quarts water), uncovered, until crisp-tender, about 3 minutes. Drain and transfer to a bowl of cold water to stop cooking. Drain again. Pat pork dry, then cut across the grain into ÿ-inch-thick slices (about 2 by 1 inch). Heat oil in a 12-inch skillet over high heat until it shimmers, then cook seasoning paste, stirring constantly, until fragrant, about 1 minute. Add pork, tossing to coat, then spread out in skillet and brown, turning occasionally (to keep paste from burning), about 2 minutes. Add fish sauce, palm sugar, and beans and cook, tossing, until pork is just cooked through and beans are hot, about 1 minute. Remove from heat and toss with lime leaves.
3. Cook beans in a medium saucepan of boiling salted water (1 teaspoon salt for 2 quarts water), uncovered, until crisp-tender, about 3 minutes. Drain and transfer to a bowl of cold water to stop cooking. Drain again.
4. Pat pork dry, then cut across the grain into ÿ-inch-thick slices (about 2 by 1 inch).
5. Heat oil in a 12-inch skillet over high heat until it shimmers, then cook seasoning paste, stirring constantly, until fragrant, about 1 minute. Add pork, tossing to coat, then spread out in skillet and brown, turning occasionally (to keep paste from burning), about 2 minutes. Add fish sauce, palm sugar, and beans and cook, tossing, until pork is just cooked through and beans are hot, about 1 minute. Remove from heat and toss with lime leaves.