Rinse the quinoa under cold water, then combine with the water in a small pot; bring to a boil, reduce to low, cover, and simmer for 15 minutes until fluffy.
Preheat your oven to 400°F and toss the broccoli florets and diced red bell pepper with half of the olive oil and a pinch of the sea salt on a parchment-lined baking sheet.
Roast the vegetables for 15-18 minutes until the broccoli edges are crispy and the peppers are tender.
While vegetables roast, season the chicken breast evenly with the dried oregano, remaining sea salt, and black pepper.
Heat the remaining olive oil in a skillet over medium-high heat and sear the chicken for 6-7 minutes per side until golden brown and cooked through.
During the last minute of cooking the chicken, add the minced garlic to the skillet and sauté until fragrant, then finish with a squeeze of fresh lemon juice.
Slice the chicken and serve it over the cooked quinoa with the roasted vegetables on the side.