Start by combining all the ingredients in a blender or food processor. The balsamic vinegar adds a tangy, slightly sweet base, while the Dijon mustard serves as an emulsifier to bind the flavors together. Add whole garlic cloves for a robust kick, Worcestershire sauce for umami depth, and finally the lemon zest and seasonings to brighten things up. Blend it all until smooth and aromatic.

Place your steak in a large ziplock bag or an airtight container. Pour the marinade over the meat, ensuring it’s completely coated. Seal the bag or cover the container, then refrigerate for at least 30 minutes. For a deeper flavor, allow the steak to marinate for up to 2 hours. Be sure not to over-marinate, as the acidity from the vinegar can break down the meat too much.

Once marinated, remove the steak from the fridge and let it come to room temperature for about 15-20 minutes. Heat a grill or cast-iron skillet to high heat to get it searing hot. Lay the steak on the grill or skillet and cook each side for 3-4 minutes for a medium-rare finish. Use tongs to flip the steak and avoid piercing the meat to retain the juices.

Once cooked, transfer the steak to a cutting board and allow it to rest for 5-10 minutes. This resting period lets the juices redistribute throughout the meat, ensuring every bite is tender and moist. When ready to serve, slice the steak against the grain for optimal texture.