Preheat your oven to 400°F and line a baking sheet with parchment paper.
Combine the dry quinoa and water in a small pot, bring to a boil, then reduce heat and simmer covered for 15 minutes until liquid is absorbed.
Place the chopped bell pepper, zucchini, and red onion on the baking sheet and toss with half of the olive oil and a pinch of the sea salt.
Roast the vegetables for 20 minutes until they are tender and slightly caramelized.
Season the chicken breast with dried oregano, the remaining sea salt, and black pepper.
Grill or pan-sear the chicken over medium-high heat for 6-7 minutes per side until the internal temperature reaches 165°F.
Slice the cooked chicken into bite-sized strips.
In a large bowl, fluff the cooked quinoa with a fork and fold in the roasted vegetables, sliced chicken, and crumbled feta cheese.
Drizzle the remaining olive oil and fresh lemon juice over the mixture and toss gently before serving.