In a large Dutch oven over medium heat, heat the oil. Add the flour, a little at a time, blending well with a whisk. Cook, stirring, until golden brown, about 4 to 6 minutes.
Add the chopped onions, celery, and bell pepper. Cook, stirring, for 4 minutes. Reserve about 3 tablespoons of the sliced green onion tops for garnish and add the remaining sliced green onions to the pot. Cook, stirring, for another minute. Add the tomatoes, tomato paste, and water. Stir to blend. Add the corn, ham, sausage, salt, crushed and cayenne pepper, and Tabasco. Bring to a boil.
Reduce heat to low. Partially cover the pot and simmer, stirring occasionally, for 1 hour.
Garnish with the reserved green onion tops.
Calories per serving: 448
Fat per serving: 28.7