Prepare the cream sauce by combining the yogurt, mayonnaise and cucumber in a small bowl. Stir in wasabi and garlic salt to taste.
Heat a medium skillet over medium high heat. Pat the fish dry. Drizzle with olive oil and lightly rub the oil to cover the surface of each filet. Sprinkle both sides with garlic salt and pepper. Coat a skillet with cooking spray and sear the filet for 3 to 4 minutes on each side (you’ll notice the bottom of the filet will turn opaque and will loosen easily from the pan when each side is done. If the fish seems to be stuck to the pan, it may need more searing.) Remove from heat when the filet is almost cooked through (it will continue cooking even after it’s removed from the pan). This way, your fish will be moist and done to perfection!
To serve, top each filet with a large dollop of cream sauce. Garnish with scallion and serve with rice, couscous or quinoa.