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, 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 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 a Grill or Grill Pan over medium-high heat. Remove the 1 ½ lb boneless skinless chicken breasts pounded to even thickness from the marinade and grill for 5–7 minutes per side, until the internal temperature reaches 165°F and grill marks form. Transfer to a Cutting Board, rest for 5 minutes, then slice against the grain.

In a large Mixing Bowl, combine the chopped 1 large romaine lettuce chopped into bite-sized pieces, 2 medium roma tomatoes cut into wedges wedges, sliced 1 whole English cucumber halved lengthwise and sliced, 0.5 whole red onion thinly sliced, 1 whole green bell pepper seeded and sliced into strips strips, and ½ cup kalamata olives pitted. Drizzle with the dressing and toss gently to coat.

Divide the dressed salad among four plates or bowls. Top each with sliced grilled 1 ½ lb boneless skinless chicken breasts pounded to even thickness and crumbled 6 oz feta cheese crumbled or sliced into a block. Serve immediately.