Preheat oven to 250 degrees.
Toss fish with 2 tablespoons olive oil and creole seasoning. Set aside.
In a large cast iron skillet, heat remaining 4 tablespoons olive oil over medium-high heat until it sizzles. Gently place the fish fillets in the skillet. Cook on one side for 3-4 minutes. Carefully turn fish fillets and continue cooking until the fish is cooked through. If you can easily insert a toothpick into the fish, it is done. Remove to an ovenproof platter. Place in oven to keep warm while cooking remaining fillets.
While fish is cooking combine salad greens with dressing. Toss thoroughly. Divide greens among four dinner plates.
On top of salads, sprinkle red onions, cherry tomato halves and pepper slices.
Top each salad with a fish fillet and serve immediately.