Heat a frying pan over high heat. Sauté shallot, lemongrass, ginger root, green chile, and garlic 2 minutes or until golden. Take out of pan and reserve.
Spray pan with cooking spray and pour in oil; heat over medium-high heat. Cook shrimp 3 minutes or until opaque.
Boil a large pot of water. Mix in shallot mixture, lower heat, and simmer 10 minutes. Stir in mushrooms and simmer 2 minutes. Take pot off of heat and add in shrimp, lime juice, fish sauce, and chili oil. Garnish with basil.