Slice the chicken breast into even 1-inch strips to ensure uniform cooking on the grill.
Prep the vegetables by cutting the zucchini into thick half-moons and the red bell pepper into wide strips.
In a large mixing bowl, whisk together the olive oil, dried oregano, garlic powder, sea salt, black pepper, and the juice of the half lemon.
Add the chicken strips and vegetable pieces to the bowl, tossing thoroughly until every piece is evenly coated in the herb marinade.
Preheat a grill or a cast-iron grill pan over medium-high heat until it is hot enough to sizzle.
Place the chicken on the grill and cook for 5-6 minutes per side, or until the internal temperature reaches 165°F and beautiful char marks appear.
Add the zucchini and peppers to the grill alongside the chicken, cooking for 3-4 minutes per side until they are tender-crisp.
Remove everything from the heat and serve immediately while hot and juicy.