In a medium bowl, whisk together olive oil, minced garlic, lemon zest, lemon juice, oregano, thyme, smoked paprika, sea salt, black pepper, and optional red pepper flakes. Pat the chicken breasts dry, place them in a shallow dish or zip-top bag, and pour the marinade over. Ensure to turn the chicken to coat completely, cover, and refrigerate for at least 30 minutes, ideally 1-2 hours.

Rinse uncooked brown rice or quinoa under cold water until the water runs clear. In a saucepan, combine the grains with low-sodium chicken broth or water and salt. Bring the mixture to a boil, then reduce to low. Cover and let it simmer until tender, then remove from heat and let it sit covered for a few minutes to steam.

Preheat your oven to 400°F (200°C). On a parchment-lined baking sheet, arrange broccoli crowns, sliced red and yellow bell peppers, and red onion wedges. Drizzle with olive oil and season with salt, black pepper, garlic powder, and dried Italian seasoning. Toss to coat all the veggies evenly, then roast them for 18-22 minutes until golden and tender.

In a large skillet over medium-high heat, add a drizzle of olive oil. Remove the marinated chicken, allowing any excess marinade to drip off, then place it in the hot skillet. Cook until browned on one side, then flip and continue cooking until the chicken's internal temperature reaches 165°F (74°C). Let it rest before slicing.

Divide the cooked grains evenly among 4-5 meal prep containers. Layer with roasted vegetables and sliced chicken. Garnish each bowl with fresh parsley, dill or cilantro if desired, and a wedge of lemon.