Make a roux by stirring the oil and flour over slow to medium heat. When the roux has a peanut butter color, add the onions, celery, garlic, and green peppers. Saute the veggies for five minutes. In another skillet melt butter and add tomato paste. Saute paste in butter until smooth and thick, about 15 minutes, and then mix with roux. Pour in broth, water with melted bouilion cubes and the rest of the seasonings. Cook for 30 minutes. Add crawfish tails 5 minutes before serving. Serve over rice.