Step 1: Prepare the Marinade

1. In a medium mixing bowl, whisk together soy sauce, olive oil, balsamic vinegar, Worcestershire sauce, and Dijon mustard until well combined.
2. Stir in brown sugar, smoked paprika, black pepper, salt, minced garlic, onion powder, lemon juice, and red pepper flakes if using.
3. Mix everything until the sugar dissolves and the marinade is smooth.

Step 2: Marinate the Steak

1. Place the steaks in a large resealable bag or a shallow dish.
2. Pour the marinade over the steaks, ensuring each piece is fully coated.
3. Seal the bag or cover the dish and refrigerate for at least 30 minutes, or up to 24 hours for maximum flavor.

Step 3: Remove and Rest

1. Remove the steak from the marinade and let it sit at room temperature for 20–30 minutes before cooking.
2. Pat the steaks dry with a paper towel to remove excess marinade (this helps achieve a nice crust when cooking).

Step 4: Cook the Steak

1. For Grilling: Preheat the grill to 450°F (230°C) and cook for 4-6 minutes per side for medium-rare.
2. For Pan-Searing: Heat a cast-iron skillet over high heat and cook for 3-5 minutes per side, depending on thickness.
3. For Broiling: Place on a baking sheet and broil on high for 4-7 minutes per side.

Step 5: Rest and Serve

1. Let the steak rest for 5-10 minutes after cooking to allow the juices to redistribute.
2. Slice against the grain and serve with your favorite sides.