In a large saucepan, combine coconut milk with curry base over medium heat until oil appears on top. Add chicken, seasoning sauce and lemon juice. Simmer for 5 minutes, stirring occasionally.
Add remaining ingredients except mushrooms and garlic chili sauce. Cover and simmer for 5 minutes.
Add mushrooms and garlic chili sauce to taste. Cover and simmer 2 minutes.
Serve hot over rice. Garnish with sprigs of fresh sweet basil.