Pat the chicken breast dry with a paper towel and season both sides evenly with sea salt, black pepper, and dried oregano.
Heat the olive oil in a medium skillet over medium-high heat. Once hot, add the chicken breast and cook for 6-7 minutes per side until golden brown and cooked through.
While the chicken cooks, mince the garlic and dice the cucumber and cherry tomatoes into bite-sized pieces.
During the last minute of cooking the chicken, add the minced garlic to the pan and squeeze the fresh lemon juice over the meat, allowing it to deglaze the pan and coat the chicken.
Remove the chicken from the pan and let it rest for 3 minutes before slicing into thin strips.
Assemble the bowl by placing the fresh baby spinach and cooked quinoa at the base.
Top the bowl with the diced cucumber, cherry tomatoes, and sliced lemon-herb chicken.
Garnish with the crumbled feta cheese and any remaining pan juices from the skillet before serving.