Measure and rinse the quinoa: Put 2/3 cup dry quinoa in a fine-mesh sieve and rinse under cold water until the water runs clear (30–60 seconds). Rinsing removes surface saponins that can taste bitter; it also loosens dust and improves the final texture.

Cook the quinoa: Combine the rinsed quinoa and 1 1/3 cups water (and the optional bay leaf) in a small saucepan. Bring to a simmer over medium-high heat, then reduce to low, cover and cook for 12–15 minutes until water is absorbed. Remove from heat and let rest, covered, 5 minutes to steam — this makes the grains fluffy and prevents a gummy texture. Fluff with a fork and discard the bay leaf.

Prepare the chicken: Pat the 560 g chicken breasts dry with paper towels (dry surface = better browning). If breasts are thick, butterfly or pound to an even 1/2–3/4" thickness so they cook evenly. Season both sides with 1 tsp kosher salt, 1/2 tsp black pepper, 1/2 tsp garlic powder and 1/2 tsp dried oregano. The simple rub highlights the Mediterranean flavors without overpowering the chicken.

Preheat and oil the grill or skillet: Heat a grill pan or outdoor grill to medium-high (about 400°F / 200°C) or set a heavy skillet over medium-high heat. Brush 1 tbsp olive oil on the grill grates or into the pan to prevent sticking and encourage even browning. High, direct heat quickly sears the chicken, developing flavor through Maillard browning.

Grill the chicken: Place the chicken on the hot grill or pan and sear 4–6 minutes per side (depending on thickness) until a golden-brown crust forms and the internal temperature reaches 74°C / 165°F. Flip only once when the surface releases easily — frequent turning prevents a good crust. If using an outdoor grill, move to indirect heat for thicker breasts to finish cooking without charring.

Rest and slice the chicken: Transfer cooked chicken to a cutting board and let rest 5 minutes before slicing across the grain. Resting allows juices to redistribute so the breast stays moist rather than leaking out when cut.

Make the lemon-olive vinaigrette: In a small bowl or jar whisk 4 tbsp extra-virgin olive oil, 4 tbsp fresh lemon juice, 1 tsp Dijon, 2 minced garlic cloves, 1/4 tsp salt and 1/4 tsp fresh ground pepper. Whisk or shake vigorously until emulsified (the oil temporarily suspends in the lemon for a glossy dressing). Taste and adjust salt/lemon — acidity should brighten the salad without overpowering the chicken.

Assemble the salad base: In a large bowl combine 8 cups mixed salad greens, 2 cups halved cherry tomatoes and the sliced cucumbers. Spoon in the warm (or room-temperature) quinoa — mixing warm grain with greens softens them slightly and helps the dressing adhere.

Dress and toss: Pour about 3 tbsp of the vinaigrette over the salad mixture and toss gently to coat. Reserve a bit of dressing to finish the plates. Start with less dressing so the salad doesn’t become soggy; you can always add more.

Plate and finish: Divide the dressed salad among four plates, mound 1/2 cup cooked quinoa on each, top with sliced grilled chicken (about 140–150 g each). Sprinkle 1 oz (28 g) crumbled feta over each portion and scatter chopped parsley or mint. Drizzle remaining dressing, finish with a crack of black pepper and a light sprinkle of flaky salt if desired. The final drizzle and herbs add freshness and an attractive shine.

Serve immediately: Serve while the chicken is still slightly warm for the best contrast of textures — warm chicken and quinoa against crisp greens. This contrast is a signature element of a satisfying composed salad.