SOAK the noodles in boiling water for 8 minutes, then drain and rinse under cold water. PLACE equal amounts of noodles in the bottom of four large bowls. PLACE even amounts of bean sprouts, the green part of the scallions and cilantro on top of each (reserve a little scallion and cilantro for garnish). PLACE the fish, soy sauce and cornstarch in a food processor and process until the fish is minced. FORM the mixture into walnut-size balls and set aside on a plate. HEAT the oil over a medium heat and cook the curry paste, garlic and kaffir lime leaf for 1 minute. ADD the coconut milk, stock, fish sauce and brown sugar, increase the heat and bring to a rolling simmer. COOK for 2 minutes, uncovered, then add the yellow peppers, carrots and white parts of the scallions and cook for 2 minutes, uncovered. ADD the fish balls, cover with a lid, and cook for 5 minutes. REMOVE from the heat and stir in the lime juice. LADLE equal amounts of the fish ball-vegetable soup into each bowl over the noodles, and garnish with extra scallion and cilantro to serve.

Variations: Replace the fish balls with bite-size pieces of white fish or salmon. Or add chicken, shrimp, scallops, squid, mussels, tofu, or use a combination. Use other vegetables such as cabbage, broccoli, mushrooms and red pepper.