Cut the sirloin steak and vegetables into uniform pieces, about 1-inch cubes.

In a bowl, combine the olive oil, soy sauce, lemon juice, garlic powder, salt, and pepper. Stir until blended, then add the steak cubes, coating them well.

Thread the marinated steak and vegetables onto the soaked skewers, alternating between the steak and colorful veggies.

Set your grill to medium-high heat (around 400°F).

Carefully place the skewers on the grill and cook for about 10-12 minutes, turning occasionally.

Once grilled, let the kabobs rest for a few minutes before serving.