Fire up a grill, either gas or charcoal, to medium-high heat. Another option is to warm up a grill pan over high heat.

With paper towels, pat the redfish to dry.

Add 1 teaspoon of salt and 1/2 teaspoon of black pepper to the fillets' seasoning.

Mix the olive oil, garlic, lemon zest, lemon juice, Cajun spice, and red pepper flakes in a medium bowl. To taste, add salt and pepper to the marinade.

Redfish should be added to the marinade and coated. Place the fish on a baking sheet and marinate for up to 30 minutes in the fridge.

Apply neutral oil to the grill grates by brush.

Place the redfish skin-side down on the grill. Redfish should be grilled for 4-5 minutes per side, turning with tongs halfway through, until the fish steaks have grill marks and are just cooked through.

Place the fillets of redfish on a serving plate and top with green onions and fresh parsley.