- Combine the whiskey, balsamic vinegar, olive oil, Dijon mustard, onion powder, garlic powder, salt, and black pepper in a large Ziploc bag. Press around the outside of the bag with your fingers to combine.
- Place the steak cubes into the marinade. Then place the mushrooms on the top. Let marinate in the fridge for a minimum of 2 hours and up to 24 hours.
- Let wooden skewers soak in water for 2 hours minimum. This prevents them from burning.
- Slide a mushroom, then the piece of steak, and green bell pepper onto a wooden skewer. Repeat this process until the skewer is nearly full.
- Cook on the grill over medium heat, turning often for 8 -10 minutes, or until the steak is cooked and mushrooms softened. Let sit for 5 minutes, then enjoy.