Cut the chicken breast into 1-inch cubes and place them in a medium mixing bowl.
Chop the red bell pepper, red onion, and zucchini into uniform 1-inch pieces to ensure even cooking.
In a small bowl, whisk together the olive oil, lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Pour the marinade over the chicken and vegetables, tossing thoroughly to coat every piece.
Thread the chicken and vegetables onto skewers, alternating between the protein and the different vegetables.
Preheat your grill or grill pan to medium-high heat.
Place the skewers on the grill and cook for 10-12 minutes, turning occasionally, until the chicken is cooked through and the vegetables are tender with light char marks.