To make Grilled Lemon Herb Chicken with Roasted Vegetables and Quinoa, follow these simple steps:

1. Marinate the Chicken: In a bowl, combine lemon juice, olive oil, parsley, thyme, garlic powder, salt, and pepper. Add chicken breasts and marinate for at least 15 minutes. For more flavor, longer marination is recommended.

2. Cook the Quinoa: In a medium saucepan, bring the chicken broth (or water) to a boil. Add quinoa, reduce heat to low, cover, and let it simmer for about 15 minutes until the liquid is absorbed. Fluff with a fork once done.

3. Prepare the Vegetables: Preheat your oven to 425°F (220°C). On a baking sheet, arrange the sliced bell pepper, zucchini, and red onion. Drizzle with olive oil, season with salt, pepper, and paprika, if using. Toss to coat and spread them out evenly.

4. Roast the Vegetables: Place the baking sheet in the preheated oven and roast for 20-25 minutes, or until the vegetables are tender and slightly caramelized.

5. Grill the Chicken: While the vegetables roast, heat a grill or grill pan over medium-high heat. Remove the chicken from the marinade and grill it for 5-7 minutes per side, or until fully cooked and juices run clear. Let it rest for a few minutes before slicing.