Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Slice the zucchini into half-moons, chop the red bell pepper into 1-inch pieces, and thinly wedge the red onion.
Place the chicken breast on one side of the prepared baking sheet and arrange the chopped vegetables in a single layer on the remaining space.
Drizzle the extra virgin olive oil and fresh lemon juice over both the chicken and the vegetable medley.
Evenly sprinkle the dried oregano, garlic powder, sea salt, and black pepper over all the ingredients on the pan.
Toss the vegetables with your hands or tongs to ensure they are well-coated, and turn the chicken to season both sides.
Roast for 20 to 25 minutes, or until the chicken is cooked through to an internal temperature of 165°F and the vegetables are lightly caramelized.
Remove from the oven, let the chicken rest for 5 minutes before slicing, and garnish the vegetables with crumbled feta cheese.