In a medium bowl, whisk together olive oil, apple cider vinegar, and crushed garlic until well combined. Stir in salt and pepper, then add capers, red onion, and parsley. Set aside.

Heat a large sauté pan over medium heat and add olive oil and butter. Once bubbling, season fish fillets with salt and pepper and cook for 3-4 minutes on each side until done.

Remove fish from the pan, drain on kitchen towels, and arrange on a platter. Spoon dressing over the fish and let it rest for 15 minutes before serving.