Pat the steak dry and cut into 1 1/2 inch thick cubes.

In a large mixing bowl, combine the marinade ingredients and whisk to combine. Reserve 2-3 tablespoons of marinade to brush onto the kabobs after cooking.

Add the steak cubes into the bowl and toss to coat each piece in the marinade. Cover and refrigerate for at least 4 hours, or up to overnight.

Prepare the vegetables by rinsing and drying them. Deseed the bell peppers and cut into large 1 1/2 inch wide squares. Slice the zucchini or yellow squash into thick 1/4 inch rounds. Peel the onions and cut into 1 1/2 inch wide squares. Trim mushrooms stems, do not remove them completely.

Remove the beef from the refrigerator. Take a metal skewer and thread the beef and vegetables loosely on. You do not want to overcrowd them and press them into each other. Leave a little space between so it heats and cooks the pieces evenly.

Grill the kabobs over high heat on a preheated grill or a large skillet over stovetop. Grill for 8-12 minutes, flipping it and cooking on each side for 2-3 minutes, until medium rare and the veggies start to char around the edges. If cooking in the oven, bake in a preheated oven at 400 F for 10-15 mins each side, then broil on high for 2 minutes, or until charred. Use a meat thermometer to properly gauge cooking times and cook to an internal temperature of 130-135 F for medium-rare, 140-150 F for medium-well, and 160-165 F for well done. The temperature will continue to rise as it rests, so remove it on the lower end of the temperature scale for medium-rare, medium, or well.

Place the cooked kabobs onto a baking tray and allow to rest for 5-10 minutes before serving. Brush with reserved marinade (that did not have raw meat in it) then garnish with fresh parsley. Serve with your favorite dipping sauces, rice, mashed potatoes, salad, or corn.