Vegetarian Gumbo

Whisk flour and oil in a 7-quart pot. Cook over medium heat, stirring frequently, until the mixture is deeply browned (the color of milk chocolate), 10 to 12 minutes. Add squash, onions, poblanos and celery; cook, stirring occasionally, until the vegetables are well coated and warmed through, about 5 minutes. Stir in broth, crushed tomatoes and salt; bring the mixture to a boil over high heat. Stir in okra; reduce heat to medium-high and simmer for 5 minutes. Stir in zucchini and beans; simmer until the squash is tender, about 5 minutes. Stir in hot sauce, vinegar and pepper. Serve over rice.