1. Preheat oven to 400F. Roast potatoes 40 minutes or until soft. Cook and peel.
2. Add lemongrass, thai chiles, shallots, galangal root (or cilantro stems)and garlic cloves to a food processor and pulse until finely minced. Heat sesame oil in a saucepan; add lemongrass mixture and saute 10 minutes or until tender and fragrant. Add lime juice and fish sauce to deglaze pan.
3. Add stock. coconut milk and salt and pepper. Reduce heat and simmer for 30 minutes. Puree with an immersion blender (or leave a bit chunky). Serve with coconut cream, cilantro and sesame seed brittle.
Note: you can also add tofu, chicken or turkey to this soup for a main dish meal. Serve over basmati or jasmine rice.