In a bowl, whisk together the soy sauce, balsamic vinegar, olive oil, Worcestershire sauce, and freshly minced garlic until combined. Stir in the brown sugar and dried rosemary until the sugar dissolves. This creates a well-balanced marinade with savory, sweet, and acidic components that will tenderize and flavor the meat. Set aside about 1/4 cup of marinade separately before proceeding—you'll use this later to make a pan glaze.

Pat the ribeye steaks dry with paper towels, then season both sides generously with salt and freshly ground black pepper. This helps develop a better crust when searing. Place the steaks in a resealable bag or shallow dish and pour the marinade (minus the reserved portion) over them, making sure they're well coated. Seal and refrigerate for at least 30 minutes, or up to overnight—I find that overnight marinating gives you deeper flavor penetration, especially with tougher cuts, though even 30 minutes makes a noticeable difference.

Remove the steaks from the refrigerator about 15 minutes before cooking to bring them closer to room temperature—this ensures more even cooking throughout. While they rest, heat your grill to 400-450°F until it's hot and ready to sear. Lightly oil the grill grates to prevent sticking.

Remove the steaks from the marinade, allowing excess liquid to drip off. Place them on the hot grill and cook for 6 minutes on the first side without moving them—this creates a flavorful crust. Flip and cook for another 6 minutes on the second side. Check the internal temperature with a meat thermometer; aim for 130-140°F for medium-rare. Remove the steaks from the grill and transfer to a cutting board.

While the steaks rest, pour the reserved 1/4 cup of marinade into a saucepan over medium-high heat. Let it simmer and reduce for 3-5 minutes, stirring occasionally, until it becomes thick and syrupy—this concentrates the flavors and creates a glossy glaze. Meanwhile, tent the cooked steaks loosely with foil and let them rest for 10 minutes; I like to rest my steaks this way to allow the juices to redistribute throughout the meat, which keeps them tender and juicy when you cut into them.

Transfer the rested steaks to serving plates and drizzle the warm pan glaze over the top. Serve immediately while the steaks are still warm and the glaze is glossy.