Whisk together the lemon juice, minced garlic, and a pinch of dried oregano to create a simple marinade.
Place the chicken breast in a shallow dish, coat with the marinade, and let it rest for 15 minutes.
Preheat your oven to 400°F and line a baking sheet with parchment paper.
Toss the broccoli florets with olive oil and a dash of sea salt, then spread them evenly on the baking sheet.
Roast the broccoli for 15-20 minutes until the edges are tender and slightly charred.
While the broccoli is roasting, heat a grill pan or outdoor grill over medium-high heat.
Grill the chicken breast for 6-7 minutes per side, ensuring the internal temperature reaches 165°F.
Warm the pre-cooked quinoa in a small saucepan or microwave if needed.
Slice the grilled chicken and serve it over the quinoa alongside the roasted broccoli.