Preheat oven to 425°F and line a baking sheet with parchment paper.
Cut the cabbage into thick wedges, keeping the core intact so they hold together.
Brush cabbage wedges with half the olive oil and season with a pinch of sea salt and black pepper.
Roast cabbage for 20 minutes, flipping halfway through, until edges are golden and crispy.
While cabbage roasts, heat the remaining olive oil in a skillet over medium-high heat.
Add ground turkey, breaking it apart with a spatula, and season with garlic powder, onion powder, sea salt, and black pepper.
Cook turkey until browned and cooked through, about 8 minutes.
Stir in fresh parsley, dill, and lemon juice to the turkey mixture.
Serve the herb-seasoned turkey over the roasted cabbage wedges.