Preheat your oven to 400°F and heat a grill or grill pan over medium-high heat.
In a small bowl, whisk together half of the olive oil, the lemon juice, lemon zest, minced garlic, and dried oregano to create the marinade.
Brush the chicken breast thoroughly with the marinade and season with half of the sea salt and black pepper.
On a large parchment-lined baking sheet, toss the broccoli florets and sliced red bell peppers with the remaining olive oil, salt, and pepper.
Roast the vegetables in the oven for 15-20 minutes until they are tender and show slight charred edges.
While the vegetables roast, place the chicken on the hot grill and cook for 6-7 minutes per side, or until the internal temperature reaches 165°F.
Allow the chicken to rest for 5 minutes before slicing.
Serve the grilled chicken and roasted vegetables over the warm, cooked quinoa.