Step 1

Set a large stock pot of salted water over high heat and bring to a boil. Meanwhile, heat oil in a large saucepan over medium-high heat until shimmering. Add curry paste and cook, pressing it into the bottom of the pan with a wooden spoon until fragrant and sizzling, about 1 minute. Whisk in chicken broth, fish sauce, sugar, and lime juice. Add chicken breast halves.

Step 2

Allow mixture to come to a simmer and cook until chicken is cooked through, about 10 minutes. Transfer chicken to a bowl and, wearing gloves or working under cold running water, tear chicken into bite-sized strips.

Step 3

Cook noodles in boiling water according to package instructions.

Step 4

To serve, divide noodles and chicken between four large bowls. Season broth to taste with more lime juice, fish sauce, sugar, and salt as desired, then pour over chicken and noodles. Divide herbs and scallions between bowl, and serve immediately with extra lime wedges.