Prepare the tapenade by combining all ingredients in a medium bowl. Stir to combine, then transfer half the mixture to a food processor and quickly pulse until finely chopped, but not smooth. Return to the bowl and stir to combine with the rest of the tapenade. Cover and set aside.
Add the olive oil to a large non-stick skillet set over medium heat. Season the fish fillets with salt and black pepper, to taste, and add to the hot skillet. Cook for 3-4 minutes, or just until golden brown, then turn and cook on the other side for another 3-4 minutes. Repeat on each edge for 1 minute or just until golden. Do not overcook.
Add the tapenade and Feta cheese to the skillet and cook, stirring continually, just until heated through - approximately 1-2 minutes. Remove from heat and transfer the fillets to individual serving plates. Spoon some of the warm tapenade over each fillet and serve immediately with lemon wedges.