Shrimp Étouffée Recipe

Name: Shrimp Étouffée Recipe
Ingredients: 2 pounds (900g) shell-on shrimp, or 3 pounds (1.4kg) head-on shrimp (small or large shrimp will work in this recipe; size doesn't matter); 2 teaspoons (8g) Diamond Crystal kosher salt; for table salt, use about half as much by volume; 1/2 teaspoon baking soda; 3 tablespoons (45ml) vegetable or canola oil; 1 medium yellow onion, diced; 2 large ribs celery, diced; 4 medium cloves garlic, smashed; 2 tablespoons (30ml) tomato paste; 1/2 cup (120ml) dry sherry or brandy (optional); 1 bay leaf; A few sprigs flat-leaf parsley; 4 sprigs thyme; 1/2 cup (4 ounces; 115g) unsalted butter; 1/2 cup (2 1/4 ounces; 65g) all-purpose flour; 1 (8-ounce; 225g) medium yellow onion; 2 large ribs celery (6 ounces; 170g), diced; 1 (8-ounce; 225g) large green bell pepper, stemmed, seeded, and diced (or, if you want a sweeter flavor, half of a large green bell pepper and half of a large red bell pepper); 4 medium cloves garlic, coarsely chopped; 3 scallions, white and light-green parts only, thinly sliced, plus more for garnish; 1/2 teaspoon dried oregano; 1/2 teaspoon dried thyme; 1/4 teaspoon garlic powder; 1/4 teaspoon onion powder; 1/4 teaspoon cayenne pepper; 1/8 teaspoon hot paprika (optional); 3 cups (700ml) shrimp stock, plus more as needed; 2 bay leaves; Kosher salt and freshly ground black pepper; Warm long-grain rice, for serving