"A filling Thai noodle soup with tons of flavor. The leftovers are even better cold the next day! You can add meat instead of tofu, make it vegetarian by using vegetable broth, or change up the veggies with whatever you have on hand."
Heat 1 tablespoon peanut oil in a large saucepan over medium heat. Add lemongrass, lime juice, ginger, garlic, and red pepper flakes; heat until fragrant, about 30 seconds. Add onion; cook and stir until soft, about 5 minutes. Add remaining 1 tablespoon peanut oil and tofu; stir-fry until tofu is lightly browned, about 5 minutes.
Combine water, chicken stock, coconut milk, soy sauce, fish sauce, and brown sugar in a large pot; bring to a boil. Pour in lemongrass mixture. Simmer over low heat until flavors combine, about 20 minutes. Add bok choy and rice noodles; cook until tender, about 5 minutes. Garnish with cilantro.