Ingredients

• 2 lb large shrimp in shell (21 to 25 per lb), peeled and shells reserved
• 14 cups water
• 1/4 cup vegetable oil
• 1/2 cup all-purpose flour
• 2 medium onions, chopped
• 2 celery ribs, chopped
• 1 large green bell pepper, chopped
• 1/2 lb fresh or frozen pork tasso* (Cajun-cured smoked meat), thawed if frozen, trimmed and cut into 1/4-inch pieces
• 1 1/2 teaspoons salt
• 1/2 teaspoon cayenne
• 10 oz fresh or frozen baby okra, thawed if frozen, trimmed, and cut into 1/4-inch-thick rounds (2 cups)
• 3/4 cup thinly sliced scallion greens
• Accompaniments: cooked white rice; hot pepper sauce
• Available at cajungrocer.com

Instructions

1. Simmer shrimp shells and water, uncovered, in an 8-quart pot until liquid is reduced to about 12 cups, 15 to 20 minutes, then pour through a sieve set over a large bowl and discard shells.
2. Stir together oil and flour in a 10-inch heavy skillet (preferably cast-iron) with a flat metal or wooden spatula, then cook over moderately low heat (do not use a high-BTU burner), scraping back and forth constantly (not stirring) until roux is the color of milk chocolate, 30 to 45 minutes. (As roux cooks, it may be necessary to lower the heat to prevent scorching.) Add onions, celery, and bell pepper and cook, scraping back and forth occasionally, until onion is softened, about 8 minutes.
3. Scrape roux mixture into cleaned 8-quart pot, then add shrimp stock and bring to a boil, stirring occasionally. Reduce heat, then add tasso, salt, and cayenne and simmer, uncovered, 30 minutes. Add okra and simmer until tender, 5 to 8 minutes. Stir in shrimp and simmer until just cooked through, 2 to 3 minutes. Stir in scallion greens and salt to taste.