Prep the chicken. If your chicken breasts are thick on one end, pound them gently to an even thickness (about 3/4 inch). This helps them cook evenly and stay juicy.

Make the marinade. In a bowl, whisk together lemon zest, lemon juice, olive oil, garlic, oregano, smoked paprika, salt, and pepper. Taste and adjust seasoning—look for a bright, slightly salty, garlicky profile.

Marinate. Add chicken to a large zip-top bag or bowl and pour in about two-thirds of the marinade. Reserve the remaining third for the vegetables. Marinate the chicken for 30 minutes to 4 hours in the fridge. Don’t go overnight; too much acid can make the texture mealy.

Prep the vegetables. Slice bell peppers into thick strips, onion into wedges, and zucchini/yellow squash into 1/2-inch rounds or long planks. Toss with the reserved marinade and a pinch of extra salt.

Heat the grill. Preheat to medium-high (about 425–450°F). Clean and oil the grates to prevent sticking. If using a grill pan, heat it until it’s hot and lightly brush with oil.

Grill the vegetables first. Place peppers and onions on the hottest area, and zucchini/squash on a slightly cooler zone. Cook 3–5 minutes per side until tender with light char. Remove to a platter and tent with foil.

Grill the chicken. Shake off excess marinade and place chicken on the hot side. Grill 4–6 minutes per side, flipping once, until an instant-read thermometer reads 165°F at the thickest point. If browning too quickly, move to a cooler area to finish.

Rest and finish. Transfer chicken to a cutting board and rest 5 minutes. Sprinkle chopped parsley or dill over the chicken and vegetables. Serve with lemon wedges for a final squeeze.

Optional serving ideas. Plate over couscous, quinoa, or rice. Add a dollop of Greek yogurt or tzatziki. For extra pop, drizzle a little olive oil and a pinch of flaky salt right before serving.