Rinse and toast the quinoa: Place 1 cup (≈170 g) quinoa in a fine sieve and rinse under cold running water until water runs clear — this removes the naturally bitter saponin coating. Drain thoroughly. In a medium saucepan, heat 1 teaspoon olive oil (or a small pat of butter) over medium heat, add the drained quinoa and toast, stirring, for 1–2 minutes until it smells nutty. Toasting deepens the flavor and keeps the cooked grains fluffy.

Cook the quinoa: Add 2 cups water or low-sodium stock and a pinch of salt to the toasted quinoa, bring to a boil, then reduce to a low simmer, cover and cook for 12–15 minutes until the liquid is absorbed. Turn off the heat and let it rest, covered, for 10 minutes to steam — this finishes cooking gently and gives a light, tender texture. Fluff with a fork and set aside to cool slightly.

Make the lemon-herb marinade for the chicken: Zest the lemon (reserve zest for finishing) then juice it to yield about 2 tablespoons. In a small bowl combine 1 tablespoon olive oil, 1 tablespoon lemon juice, 1/2 tsp garlic powder, 1/2 tsp salt, 1/4 tsp black pepper and half the chopped parsley/cilantro. Whisk to emulsify. The acid in the lemon brightens flavor and the oil helps transfer heat and prevent sticking while grilling.

Marinate the chicken: Pat the chicken breasts dry (this helps get a good sear), then brush or pour the lemon-herb marinade over them and rub it in. Let sit at room temperature for 10–15 minutes (short marination lets the surface pick up flavor without 'cooking' the meat from the acid). If you prefer, marinate up to 1 hour in the fridge.

Preheat grill or skillet: Heat a grill pan or outdoor grill to medium-high (about 200–230°C / 400–450°F) or place a heavy skillet over medium-high heat and add a thin film of oil. A hot cooking surface creates Maillard browning (a golden crust) that adds savory, caramelized flavor and texture.

Grill or sear the chicken: Place the chicken on the hot grill or skillet and cook without moving for 4–6 minutes on the first side to develop a golden crust. Flip and cook another 4–6 minutes until an instant-read thermometer in the thickest part reads 74°C / 165°F. Cooking quickly over high heat seals in juices; using a thermometer avoids overcooking, which makes breast meat dry.

Rest and slice the chicken: Transfer the cooked breasts to a cutting board and tent loosely with foil for 5–8 minutes. Resting lets the muscle fibers relax and the juices redistribute; slicing right away causes them to run out and dry the meat. Slice thinly against the grain for the most tender bites.

Prepare the salad base: While the chicken finishes resting, halve the cherry tomatoes, slice the cucumber, and arrange the mixed greens in a large bowl. Halving tomatoes releases a little juice that mingles with the dressing and gives bursts of sweetness in each bite.

Make the lemon-parsley dressing: In a small bowl whisk together the remaining 1 tbsp olive oil, remaining 1 tbsp lemon juice (or to taste), remaining chopped parsley/cilantro, 1/2 tsp salt, 1/4 tsp black pepper and a pinch of chili flakes if using. If the dressing is too thick, whisk in 1–2 tsp water to reach a loose, pourable consistency. Bright acidic dressing ties the salad, quinoa and chicken together.

Assemble the warm quinoa base: Fold the fluffed, slightly-warm quinoa into the salad greens and vegetables along with half the dressing — the warm quinoa will gently wilt the greens and absorb dressing flavors. Adjust seasoning: taste and add more salt, pepper or lemon if needed.

Add avocado and finish plating: Fan sliced avocado over the quinoa-salad, place the sliced grilled chicken on top, sprinkle reserved lemon zest and extra chopped herbs, and finish with a grind of black pepper and an optional pinch of chili flakes for heat. Serve immediately while the chicken is still warm against the bright chilled salad components for a pleasing temperature contrast.