Preheat the oven to 400?F.
Heat the oil in a large skillet over high heat. Add the onions, bell peppers, celery, salt, and cayenne. SautÈ for about 5 minutes, or until wilted. Add the crawfish tails and cook for about 5 minutes, stirring occasionally. Remove from the heat. Let cool for about 30 minutes.
In a mixing bowl, combine the crawfish mixture with the garlic, parsley, green onions, 3/4 cup mayonnaise, mustard, and Tabasco. Mix well. Spoon the mixture into a 1-quart casserole or into 4 individual gratin dishes or scallop shells. Mix together the bread crumbs, the remaining mayonnaise, and the rub. Spread the top of the crawfish mixture with this mixture. Bake for about 20 minutes, or until bubbly and brown.
Remove from the oven and let stand for 2 to 3 minutes before serving.
Yield: 4 first-course servings