Heat oil in a large Dutch oven over medium heat. Add flour; cook 1 minute, stirring constantly. Add onion; cook 4 minutes. Add 1 1/2 cups water; bring to a simmer. Simmer 30 minutes. Stir in crawfish and ham; cook 5 minutes. Add remaining 2 cups water, and bring to a boil. Stir in rice and remaining ingredients; cover and simmer 30 minutes, stirring occasionally.