Rinse peppers under cold water and pat dry. Slice off tops and bottoms, stand upright, and cut down along the inside to remove seeds and white ribs. Slice lengthwise into ½-inch strips; halve crosswise for shorter pieces. Keep sizes uniform so everything cooks evenly. If adding onion, slice it now. Measure out olive oil, 1 tsp salt, and pepper. Have everything ready before the pan goes on — sautéing moves fast.

Heat a large Skillet over medium heat. Add 1 tbsp olive oil per 2 peppers; warm 30–60 seconds until shimmering. Add pepper strips in a single layer — work in batches if crowded. Season with 1 tsp salt and pepper, stir to coat. Cook over medium heat, stirring every 2–3 minutes, for 6–10 minutes. At 6 minutes: slightly softened with snap. At 10 minutes: tender throughout with light color. For very soft peppers, cook 30–40 minutes over medium-low, stirring occasionally. Add garlic halfway through cooking. If browning too fast, add a splash of white wine or water and briefly cover to steam.

Preheat your Oven to 425°F. Arrange the 1 medium red onion cut into wedges wedges, 1 medium zucchini sliced into half-moons, and 1 medium red bell pepper seeded and cut into strips strips on a large Baking Sheet. Drizzle with the remaining 1 tablespoon of 4 tbsp olive oil divided, season lightly with 1 tsp salt and ½ tsp black pepper freshly ground, and toss to coat. Spread the vegetables in an even layer, leaving space in the center for the 2 lb bone-in, skin-on chicken thighs about 4–6 pieces, trimmed of excess fat.

Remove the Baking Sheet from the Oven and let the 2 lb bone-in, skin-on chicken thighs about 4–6 pieces, trimmed of excess fat rest for 5 minutes. Scatter the crumbled ¾ cup feta cheese crumbled over the top, garnish with 2 tbsp fresh parsley roughly chopped, for garnish, and serve directly from the pan with warm pita bread or a simple green salad on the side.