In a small bowl, whisk together the olive oil, chili powder, cayenne pepper, sea salt, and black pepper to create a spicy marinade.
Coat the chicken breast thoroughly with the marinade and let it sit for 20 minutes to absorb the flavors.
Combine the dry quinoa and water in a small saucepan, bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes until the water is absorbed.
Preheat your grill to medium-high heat and grill the marinated chicken for 6-7 minutes per side or until the internal temperature reaches 165 degrees Fahrenheit.
While the chicken cooks, grill the sliced red bell peppers and red onions until they are tender and show charred grill marks.
Assemble the bowl by layering the baby spinach and cooked quinoa, then topping with the sliced grilled chicken and charred vegetables.
Garnish with fresh cilantro and a squeeze of lime juice before serving.