Seafood Gumbo

Ingredient:

• 3/4 cup canola oil
• 1 cup all purpose flour (about 4 1/4 ounces)
• 1 large yellow onion, chopped (about 2 cups)
• 2 large celery stalks, chopped (about 1 cup)
• 1 green bell pepper, chopped (about 1 cup)
• 4 garlic cloves, finely chopped (about 4 teaspoons)
• 1 cup tomato puree (from 1 [15-ounce] can)
• 2 tablespoons kosher salt
• 1 tablespoon black pepper
• 1 1/2 teaspoons cayenne pepper
• 1 1/2 teaspoons onion powder
• 1 teaspoon garlic powder
• 1 teaspoon paprika
• 1 teaspoon dried or fresh thyme leaves
• 3 dried bay leaves
• 4 quarts chicken stock
• 1 pound fresh or thawed frozen okra, cut into 1/4-inch-thick slices (about 4 cups)
• 2 tablespoons olive oil
• 1 1/2 pounds roasted boneless, skinless chicken breasts and thighs, cut into 1-inch pieces (about 4 cups)
• 8 ounces andouille sausage (such as Zummo’s), halved lengthwise and cut into 1/4-inch-thick slices
• 2 (6-ounce) raw blue crabs, cleaned and quartered
• 6 dashes (about 1 1/2 teaspoons) hot sauce (such as Crystal or Louisiana), plus more for serving
• 2 tablespoons filé powder, plus more for garnish
• 1 pound raw large shrimp, peeled and deveined
• 1 cup chopped fresh flat-leaf parsley
• 3 scallions, trimmed and thinly sliced, plus more for garnish
• Cooked jasmine rice and cornbread, for serving