Marinate the chicken: Combine olive oil, garlic, lemon juice and zest, oregano, paprika, salt, and pepper. Coat chicken and let sit at least 15 minutes.
Cook the quinoa: Bring broth to a boil, add rinsed quinoa and salt. Simmer 15 minutes until liquid is absorbed, then fluff with a fork.
Roast the vegetables: Preheat oven to 425°F (218°C). Toss zucchini, bell pepper, onion, and cherry tomatoes with olive oil, oregano, salt, and pepper. Roast 20–25 minutes until tender.
Cook the chicken: Heat a skillet over medium-high heat and cook chicken 5–6 minutes per side until golden and fully cooked (internal temp 165°F / 74°C). Rest 5 minutes, then slice.
Assemble the bowls: Divide quinoa into meal prep containers or bowls, top with roasted vegetables and sliced chicken. Sprinkle parsley and optional toppings, drizzle with lemon juice.