Combine celeriac, fennel, and juice in a large bowl. Combine sour cream and next 4 ingredients (through pepper), stirring with a whisk. Add sour cream mixture, onions, and parsley to celeriac mixture; toss well. Cover and chill at least 30 minutes.

Rub each side of fillets with Cajun Spice Mix. Heat 2 1/2 teaspoons oil and 2 1/2 teaspoons butter in a large nonstick skillet over medium-high heat. Add 5 fillets; cook for 4 minutes on each side or until fish flakes easily when tested with a fork or until desired degree of doneness. Repeat procedure with remaining oil, butter, and fillets. Serve with lemon wedges.

Melt butter in a large skillet over medium-high heat. Add corn, onion, and pepper; sauté for 10 minutes or until corn begins to brown. Add tomatoes, Cajun Spice Mix, salt, and broth; cook 20 minutes or until liquid almost evaporates, stirring occasionally.

Bring broth and bay leaves to a boil in a medium saucepan; add rice. Cover, reduce heat, and simmer for 20 minutes or until liquid is absorbed. Discard bay leaves. Place rice in a large bowl.

Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add onion and next 5 ingredients (through garlic); sauté 7 minutes. Add sausage mixture and parsley to rice, tossing to combine.