If you want a soup with less fat, it is possible to substitute light coconut milk for one or both cans of regular coconut milk. Fresh lemon grass can be omitted. If you want a spicier soup, add more red curry paste to taste. For a more substantial meal, serve the soup over 2 to 3 cups of cooked jasmine rice. The soup can be prepared through step 1 up to one day ahead of time and refrigerated, but it should be completed immediately before serving, as the chicken and mushrooms can easily overcook.