Cut the chicken breast into uniform 1-inch cubes and place them in a medium glass bowl.
In a small jar or bowl, whisk together the extra virgin olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Pour the marinade over the chicken cubes, tossing well to ensure every piece is coated, and let marinate for at least 15 minutes.
While the chicken marinates, prep the red bell pepper, zucchini, and red onion by cutting them into pieces similar in size to the chicken cubes.
Thread the marinated chicken and vegetables onto skewers, alternating between the meat and the various colorful produce.
Preheat a grill or a cast-iron grill pan over medium-high heat until it is hot and lightly smoking.
Place the skewers on the grill and cook for 10 to 12 minutes, turning every few minutes, until the chicken is cooked through and the vegetables have a light char.