Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Cut the cabbage into thick wedges, keeping the core intact so they hold together during roasting.
Place the cabbage wedges on the baking sheet, drizzle with half of the olive oil, and season with a pinch of sea salt and black pepper.
Roast the cabbage for 20 to 25 minutes, flipping halfway through, until the edges are deeply browned and caramelized.
While the cabbage roasts, season the chicken breast with the dried oregano and the remaining salt and pepper.
Heat the remaining olive oil in a skillet over medium-high heat and sear the chicken for 6 to 7 minutes per side until golden and cooked through.
In a small bowl, whisk together the lemon juice, minced garlic, and finely chopped fresh parsley to create the dressing.
Allow the chicken to rest for 3 minutes before slicing it into strips.
Arrange the roasted cabbage and sliced chicken on a plate and finish by drizzling the lemon-herb dressing over the entire dish.