Heat oil, add flour and cook to deep brown, stirring constantly. Add onions and cook slowly about 3 or 4 minutes. Slowly add the 1-1/2 cups water. Allow this to simmer, uncovered, until reduced to 1/2 cup (about 30 or more minutes).
Add crawfish tails and cook until they turn pink. Add the 2 cups water and bring to boil. Stir in the rice and all other ingredients. Cover, reduce heat and cook until rice is dry, about 30 minutes.