How to Make It
In a mini food processor, puree the turmeric, ginger, shrimp paste, 1 chile and 2 tablespoons of the oil until a paste forms. Scrape into a large bowl, add the fish and toss to coat. Season with salt and pepper and toss again. Cover; let marinate in the refrigerator for 4 hours.
In a large, deep baking dish, cover the rice noodles with boiling water and let stand until softened, about 20 minutes. Drain well, then transfer to 4 bowls.
In a small bowl, whisk the stock with the lime juice, fish sauce, sugar, 1 garlic clove and the remaining chile.
In a large cast-iron skillet, heat the remaining 1/4 cup of oil until shimmering. Add the fish and cook over moderately high heat, turning once or twice, until browned and cooked through, about 5 minutes. Using a slotted spoon, transfer to the bowls.
Add the onion to the skillet and cook over moderately high heat, stirring occasionally, until browned and softened, about 5 minutes. Add the scallions and the remaining garlic and cook, stirring, until just softened, about 1 minute. Remove from the heat; stir in the herbs. Spoon over the fish and top with the peanuts and shallots. Serve right away, passing the sauce and lettuce leaves at the table.