Preheat your oven to 400°F.
In a bowl, combine the herb and spice blend (garlic powder, cumin, coriander, paprika, salt, and pepper) with a drizzle of olive oil and fresh lemon juice.
Pat the chicken breast dry and rub the spice mixture evenly over the surface.
Place the chicken breast on a baking tray lined with parchment paper and roast in the oven for 20-25 minutes, or until the internal temperature reaches 165°F.
While the chicken is roasting, chop mixed vegetables (bell pepper, zucchini, red onion) and toss them with a bit of olive oil, salt, and pepper. Spread on another baking sheet and roast for about 15-20 minutes until tender and slightly charred.
Prepare cooked quinoa according to package instructions if not pre-cooked.
Slice the roasted chicken into strips and assemble the bowl by layering quinoa, roasted vegetables, and chicken. Drizzle a little extra lemon juice over the top if desired.
Serve immediately and enjoy your balanced, protein-rich shawarma bowl.