Rinse the quinoa thoroughly under cold water to remove bitterness, then combine with water in a medium saucepan.
Bring the quinoa to a boil, reduce heat to low, cover, and simmer for 15 minutes until the water is absorbed and grains are fluffy.
Cut the chicken breast into bite-sized cubes and toss with dried oregano, garlic powder, sea salt, and black pepper.
Heat the extra virgin olive oil in a large non-stick skillet over medium-high heat.
Add the chicken to the skillet and sauté for 8-10 minutes until golden brown and cooked through to an internal temperature of 165°F.
Turn off the heat and squeeze the juice of both lemons over the chicken, scraping the bottom of the pan to incorporate the flavorful bits.
Slice the cucumber into half-moons and halve the cherry tomatoes.
To assemble, place 1 cup of baby spinach in each of five bowls, then top with equal portions of quinoa, lemon chicken, cucumbers, and tomatoes.