Cut the chicken breast into 1-inch cubes and chop the bell pepper, zucchini, and red onion into similar sized pieces.
In a small bowl, whisk together the olive oil, lemon juice, minced garlic, dried oregano, sea salt, and black pepper to create the marinade.
Place the chicken and vegetables in a large bowl, pour the marinade over them, and toss until everything is well coated; let it marinate for 15 minutes.
Thread the marinated chicken and vegetables onto skewers, alternating between the chicken and different colored vegetables.
Preheat your grill or grill pan to medium-high heat and lightly oil the grates.
Grill the skewers for 10-12 minutes, turning every few minutes, until the chicken is cooked through and the vegetables are tender with light char marks.
Serve the hot skewers over a bed of cooked quinoa for a complete and balanced meal.