Make the lemon‑herb marinade: in a bowl whisk together 2 tbsp (30 ml) extra‑virgin olive oil, juice of 1 lemon, minced garlic, 1/2 tsp salt, 1/4 tsp black pepper and 1/2 tsp dried oregano. Set aside 1 tbsp of this dressing for the quinoa tabbouleh. This acid + oil mixture flavors the chicken and begins to gently tenderize the exterior — but saving some for the salad keeps all components bright and coherent.

Marinate the chicken: pat the 400 g chicken breasts dry (this helps develop color), then add them to the bowl and turn to coat. Let sit at room temperature for 15 minutes (or refrigerate up to 2 hours). Do not marinate much longer than 2 hours with citrus—too much acid will start to firm the proteins and make the chicken mealy.

Preheat oven for vegetables: heat oven to 200°C / 400°F and position a rack in the middle. High heat caramelizes the vegetables’ natural sugars quickly, giving you brown edges without drying them out.

Prepare and roast the vegetables: toss the zucchini (150 g) and red bell pepper (150 g) with 1 tbsp (15 ml) olive oil, 1/4 tsp salt, a pinch of black pepper and 1/2 tsp dried oregano on a rimmed baking tray in a single layer. Roast for 20–25 minutes, tossing once halfway, until edges are golden and the pepper is charred in spots. Roast time concentrates flavor and softens the vegetables while staying slightly crisp.

Cook the quinoa: place 150 g rinsed quinoa in a small saucepan with 300 ml water and a pinch of salt. Bring to a gentle boil, reduce heat to low, cover and simmer for 12–15 minutes until the water is absorbed. Remove from heat and let rest, covered, for 5 minutes — this steaming step finishes the grains evenly. Fluff with a fork to keep the quinoa light and separate; fluffing prevents a gummy texture.

Build the quinoa tabbouleh base: while the quinoa is still a touch warm, transfer it to a large bowl and add the reserved 1 tbsp of dressing, halved cherry tomatoes (150 g), diced cucumber (100 g), finely chopped red onion (50 g), and chopped parsley (20 g). Toss gently to combine. Warm quinoa absorbs the dressing slightly, carrying flavor throughout the salad.

Grill or pan‑sear the chicken: heat a heavy skillet or grill pan over medium‑high heat until very hot. Lightly oil the grill or pan (use a brush or paper towel). Sear the chicken breasts 4–5 minutes per side (depending on thickness) until golden with good color and an instant‑read thermometer reads 74°C / 165°F at the thickest point. High direct heat builds a flavorful crust that locks juices inside. If breasts are thick, finish in a 180°C / 350°F oven for 5–8 minutes.

Rest and slice the chicken: transfer the chicken to a cutting board and rest for 6–8 minutes. Resting lets internal juices redistribute; cutting too early will let them run out and dry the meat. Slice thinly against the grain for the most tender bite.

Finish the tabbouleh and plate: fold crumbled feta (60 g) into the quinoa mixture, taste and adjust with salt, pepper and more lemon if needed. Arrange a bed of tabbouleh on each plate, top with sliced grilled chicken and a generous portion of roasted vegetables. If using, scatter 15 g toasted pine nuts over the finished plates for crunch.

Final garnish and serve: drizzle a little extra‑virgin olive oil or an extra squeeze of lemon over the chicken if desired. Serve immediately so the chicken is warm while the tabbouleh remains bright and the vegetables are caramelized and slightly hot.