Massaman Curry Chicken Noodle Soup

Name: Massaman Curry Chicken Noodle Soup
Ingredients: 6 cups chicken stock; 2 tablespoons fish sauce + more to taste; 2 stalks of lemongrass; 4″ piece of ginger root, peeled; 2 Thai chilies; 4 large garlic cloves; 2 boneless chicken breasts; 3 large carrots; 10 small baby potatoes, halved or quartered; 3 scallions, greens and white parts sliced and separated; 1 cup full fat coconut milk; 1/2 tablespoon curry powder; 12-14oz udon/rice noodles; 1/4 cup toasted peanuts; Lime juice