Mom's Grilled Beef Kabobs

Gather all necessary ingredients and supplies beforehand.

Combine soy sauce, vegetable oil, lemon juice, garlic, mustard, Worcestershire sauce, salt, and black pepper in a bowl. Mix well until all the ingredients are fully incorporated. Transfer this mixture into a resealable plastic bag, ensuring it's as full as possible. Add the beef cubes to the bag and remove any excess air, making it easier to seal later on. Close the bag tightly.

Place the marinade in the refrigerator for 8 hours or overnight, allowing the flavors to meld together and the meat to absorb all the delicious tastes.

Add sliced mushrooms to the bag, pressing out any air that might be trapped. Seal the bag once more, making sure it's secure and won't leak during storage.

Return the bag to the refrigerator for another 8 hours, allowing the mushrooms to fully absorb the flavors.

Preheat your outdoor grill to high heat and lightly oil the metal grate with a small amount of vegetable oil. Remove the beef and mushrooms from the marinade, gently shaking off any excess liquid that might be clinging to them. Pour the remaining marinade into a small saucepan and bring it to a boil over high heat, stirring occasionally.

Reduce the heat to medium-low and let the marinade simmer for 10 minutes. Set it aside, as you'll be using it to baste the skewers later.

Thread pieces of green bell pepper, beef, red bell pepper, mushroom, and onion onto metal skewers. Continue adding ingredients until all of them have been used up.

Place the skewers on the preheated grill, turning frequently to ensure even cooking. Brush the skewers generously with the marinade you prepared earlier for basting, repeating this process until they're nicely browned on all sides and the beef is no longer pink in the center, approximately 15 minutes.

Serve the skewers hot and enjoy your delicious meal!