Pat the chicken breast dry with a paper towel and season both sides evenly with sea salt, black pepper, garlic powder, and smoked paprika.
Heat the avocado oil in a medium stainless steel or cast iron skillet over medium-high heat until it begins to shimmer.
Place the chicken in the skillet and sear for 5 to 7 minutes per side, or until a golden-brown crust forms and the internal temperature reaches 165°F.
While the chicken is cooking, prepare the salad by combining the cooked quinoa, halved cherry tomatoes, diced cucumber, and finely chopped fresh parsley in a mixing bowl.
Drizzle the lemon juice over the quinoa mixture and toss thoroughly to combine the flavors.
Remove the chicken from the heat and let it rest for 3 minutes before slicing it into strips.
Plate the quinoa salad, top with the sliced chicken, and finish by sprinkling the crumbled feta cheese over the top.