Preheat the grill to medium-high heat.
In a small bowl, mix together the garlic powder, onion powder, paprika, salt, and pepper.
Thread the beef, mushrooms, bell peppers, and onion onto skewers.
Brush the skewers with olive oil and sprinkle them with the spice mixture.
Grill the skewers for about 5-7 minutes per side, or until the beef reaches your desired level of doneness.
Serve hot and enjoy!