Heat the sesame oil in a stock pot over medium heat. Add the garlic, ginger powder, whites of the green onion, shallots, red curry paste and red pepper flakes. Mix to combine and cook for 3 minutes, or until shallots begin to soften.
Add the broth, coconut milk, soy sauce, peanut butter and sweet potatoes. Bring to a boil, lower heat and simmer until the potatoes are tender (approx. 20 minutes). Right before serving, add the lime juice and cilantro.
Meanwhile, bring a pot of water to a boil and cook the noodles according to the package instructions. Drain and set aside.
To assemble, add noodles to each bowl and top with broth & potatoes. Serve with the remaining green onions.