In a large soup pot combine stock, coconut milk, potatoes, corn kernels and cobs, lemongrass and red pepper. Bring to a boil, reduce heat and simmer 25 minutes. Remove corn cobs and lemongrass. Add shrimp, cilantro and scallions; adjust seasonings. Simmer until shrimp turn pink, about 5 minutes.
Yield: 6 to 8 servings