Whisk all marinade ingredients together in a bowl. Pierce the steak with a fork to allow the flavors to penetrate, then place it in a large ziplock bag with the marinade. Seal the bag, massage the marinade into the steak, and refrigerate for 8-24 hours.
Combine all the Cajun spice mix ingredients in a bowl. This will serve double duty for seasoning the steak post-marinade and spicing up the glaze.
Remove the marinated steak from the fridge 30-60 minutes before grilling to bring it to room temperature. Rub the steak generously with olive oil and enough Cajun spice mix to coat it thoroughly.
Preheat your grill to 400°F and grease the grates. Sear the steak for 4 minutes on each side to build a flavorful crust. Lower the heat to 350°F, cover, and cook for 20-25 minutes for medium doneness, flipping halfway through. For precise results, use a meat thermometer to check. Aim for 135°F for medium-rare or 145°F for medium.
Once grilled, cover the steak with foil and allow it to rest for 10 minutes before slicing. Always slice thinly and against the grain to maintain that juicy tenderness.
While the steak cooks, whisk all glaze ingredients in a saucepan. Simmer over medium heat until thickened to a syrupy consistency. Remove from heat and serve alongside your steak or drizzle it directly on top.