Pat the ribeye steaks dry with paper towels and season both sides generously with salt and pepper.

In a small bowl, mix the cracked mustard seeds with pomegranate molasses until well combined. Spread this mixture evenly over the top of each steak, pressing lightly to adhere.

Heat olive oil in a large skillet over medium-high heat. Add the ribeye steaks, crust side down, and sear for 4-5 minutes until a golden crust forms. Flip and cook for another 3-4 minutes or until desired doneness. Remove from skillet and let rest on a plate, loosely covered with foil.

In the same skillet, add the sliced onions and cook over medium heat, stirring occasionally, until they are soft and caramelized, about 10-15 minutes. Add minced garlic and cook for another 1-2 minutes until fragrant.

Pour in the beef broth and Worcestershire sauce, scraping up any browned bits from the bottom of the skillet. Bring to a simmer and let cook for about 5 minutes to reduce slightly. Stir in the butter until melted and well combined.

Slice the ribeye steaks against the grain and place them on serving plates. Spoon the rich caramelized onion gravy over the top and garnish with fresh parsley.