2 cups chicken stock
2 cans coconut milk - light style is fine (14-ounce cans)
3 stalks lemongrass (tender inner parts only, finely minced, about 2 tablespoons)
2 tablespoons finely minced or grated and peeled fresh ginger
1 jalapeño pepper (seeded and finely minced)
3 Kaffir lime leaves (optional)
2 cups thinly sliced white button mushrooms (about 3-1/2 ounces)
3 boneless, skinless chicken breasts (about 1-1/4 pounds, cut into 1-inch strips)
1 teaspoon Sugar
2 tablespoons Thai fish sauce (preferably Three Crabs brand)
3 tablespoons fresh lime juice
1/4 cup minced fresh Thai basil or fresh cilantro