Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Toss the broccoli florets with half of the olive oil and a pinch of sea salt, then spread them in a single layer on the baking sheet.
Roast the broccoli for 15-20 minutes until the edges are tender and slightly charred.
While the broccoli roasts, rinse the quinoa under cold water and place it in a small saucepan with 1/2 cup of water.
Bring the quinoa to a boil, then reduce heat to low, cover, and simmer for 12-15 minutes until the water is absorbed.
Season the chicken breast with garlic powder, salt, and pepper.
Heat a grill pan or outdoor grill over medium-high heat and lightly coat with the remaining olive oil.
Grill the chicken for 6-7 minutes per side or until the internal temperature reaches 165°F.
Let the chicken rest for 5 minutes before slicing it into strips.
Fluff the quinoa with a fork and plate it alongside the roasted broccoli and sliced chicken.
Drizzle everything with fresh lemon juice before serving.