Heat oil in heavy large saucepan over medium heat. Add ginger and red pepper and sauté until ginger is aromatic, about 1 minute. Add stock and lime peel. Bring to boil. Stir in rice, reduce heat, cover and simmer until rice is very tender, about 20 minutes. Add shrimp, mushrooms, coconut milk and onion and cook until shrimp is opaque, about 5 minutes. Remove from heat and add lime juice. Garnish with green onions.