Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
In a medium-sized mixing bowl, whisk together the extra virgin olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Cut the chicken breast into bite-sized cubes and chop the bell pepper, zucchini, and red onion into similar-sized pieces.
Add the chicken and vegetables to the bowl with the marinade and toss thoroughly until every piece is well-coated.
Thread the marinated chicken and vegetables onto wooden or metal skewers, alternating them to create a bright and kid-friendly pattern.
Arrange the skewers on the prepared baking sheet and bake for 18 to 20 minutes, or until the chicken is fully cooked and the vegetables are slightly caramelized.
Serve the warm skewers immediately with fresh avocado slices on the side for a creamy finish.