Cambodian Num Banh Chok (Khmer Rice Noodles)

Ingredients

• 1 1/2 lb firm white fish fillets, such as tilapia, catfish or cod
• 7 cups water
• 1 1/2 tsp kosher salt, divided
• 4 lemongrass stalks, tough layers removed and tender lower cores sliced very thin
• 1 1/2 inches fresh turmeric, peeled and sliced, or 2 tsp ground turmeric
• 1 1/2 inches galangal, peeled and sliced thin
• 5 makrut lime leaves, center ribs removed and sliced thin
• 5 shallots, sliced
• 5 garlic cloves, sliced
• 1 tbsp neutral oil
• 1 to 2 tbsp commercially prepared prahok, to taste
• 3/4 cup unsweetened coconut milk
• 1 1/2 tbsp grated palm sugar
• 2 tbsp fish sauce, plus more to taste
• 1 lb fresh round rice noodles or 12 oz dried medium rice vermicelli
• 1 small banana blossom, shredded, or 3 cups finely shredded green cabbage
• 2 cups bean sprouts, rinsed and dried
• 1 English cucumber, julienned
• 8 oz yard-long beans or green beans, sliced very thin
• 1 cup mixed mint, Thai basil and culantro leaves
• 3 limes, cut into wedges
• Sliced bird's-eye chiles, for serving

Method

1. 1.Put the fish, water and 1 teaspoon salt in a wide pot. Bring just to a simmer over medium heat, then lower the heat and poach gently 8 to 12 minutes, until the thickest piece is opaque and registers 145°F.
2. 2.Lift the fish onto a plate and reserve every drop of broth. When cool enough to handle, remove skin and bones, flake the flesh and inspect it a second time for small bones.
3. 3.Pound the lemongrass, turmeric, galangal, makrut lime leaves, shallots and garlic in a large mortar until moist and fibrous with no hard chunks. Alternatively, pulse in a food processor with 2 to 3 tablespoons reserved broth, scraping often; do not dilute it into a thin smoothie.
4. 4.Add the flaked fish to the kroeung and pound or pulse briefly until the fish forms fine threads through the aromatic paste. This step gives body to the gravy without flour or starch.
5. 5.Heat the oil in a clean heavy pot over medium heat. Add the fish-kroeung paste and cook 5 to 7 minutes, stirring continuously, until the raw shallot smell fades and the turmeric color deepens without browning hard on the bottom.
6. 6.Whisk the prahok into 1 cup warm reserved fish broth, then strain through a fine sieve into the pot to catch coarse bones. Add the remaining broth, coconut milk, palm sugar, fish sauce and remaining 1/2 teaspoon salt.
7. 7.Bring the gravy to a boil, lower to a steady simmer and cook uncovered 15 to 20 minutes. Checkpoint: the broth should be aromatic, pale yellow-green and lightly textured with fish, fluid enough to soak the noodles rather than as thick as curry sauce. Add water if it becomes heavy.
8. 8.Taste a cooled spoonful. Add prahok or fish sauce sparingly for salinity and fermented depth, palm sugar only to round sharp edges, and water if the gravy tastes concentrated. Keep hot at a low simmer.
9. 9.Prepare the noodles according to their package or vendor directions. Rinse rice noodles briefly in cool water, drain extremely well and gather them into six loose coils or bowls so they remain easy to portion.
10. 10.While the noodles drain, shred the banana blossom directly into lime water, if using, then rinse and dry it. Arrange the blossom or cabbage, bean sprouts, cucumber, beans, herbs, lime wedges and sliced chiles on a large platter.
11. 11.Divide noodles among six bowls and ladle over enough hot fish gravy to wet them generously without submerging them completely. Let each diner add a large handful of raw vegetables and herbs, lime and chile, then mix before eating.
12. 12.Refrigerate gravy and noodles separately within 2 hours. Reheat the gravy to a boil and use within 3 days; prepare fresh raw vegetables for leftovers rather than storing them in the broth.