Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Chop the broccoli into small florets, slice the red bell pepper into strips, and quarter the zucchini into bite-sized pieces.
Place the vegetables on the prepared baking sheet and toss with 0.5 tablespoon of olive oil, 0.125 teaspoon of sea salt, and 0.125 teaspoon of black pepper.
Pat the chicken breast completely dry with paper towels to ensure a crispy sear, then season both sides with the remaining salt, pepper, garlic powder, and dried oregano.
Heat the remaining 0.5 tablespoon of olive oil in a cast-iron or heavy-bottomed skillet over medium-high heat until shimmering.
Place the chicken in the hot skillet and sear for 3-4 minutes on one side until a golden-brown crust forms, then flip.
Transfer the chicken breast to the baking sheet, nestling it among the vegetables, and roast in the oven for 12-15 minutes or until the internal temperature reaches 165°F.
Remove from the oven, drizzle the fresh lemon juice over the chicken and vegetables while still hot, and let the chicken rest for 5 minutes before slicing and serving.