Cut the chicken breast into even 1-inch cubes.
In a small bowl, whisk together the extra virgin olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper to create the marinade.
Place the chicken cubes in a bowl, pour the marinade over them, and toss until thoroughly coated; let marinate for at least 10 minutes.
While the chicken marinates, cut the red bell pepper, zucchini, and red onion into 1-inch chunks suitable for skewering.
Thread the marinated chicken and vegetable chunks onto skewers, alternating between the meat and the different vegetables.
Preheat a grill or grill pan over medium-high heat and lightly grease if necessary.
Grill the skewers for 10-12 minutes, turning every few minutes, until the chicken is cooked through and the vegetables have developed a light char.