In a small pot, combine the dry quinoa and water. Bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes or until water is absorbed.
While quinoa cooks, season the chicken breast on both sides with sea salt, black pepper, and garlic powder.
Heat the avocado oil in a skillet over medium-high heat. Add the chicken and sear for 5-7 minutes per side until golden brown and the internal temperature reaches 165°F.
Remove the chicken from the pan and let it rest for 5 minutes before slicing into bite-sized strips.
Halve the cherry tomatoes and dice the cucumber into small pieces.
In a small jar or bowl, whisk together the tahini, lemon juice, and warm water until the dressing is smooth and creamy.
Place the baby spinach in a large bowl. Top with the cooked quinoa, sliced chicken, tomatoes, and cucumber.
Drizzle the lemon-tahini dressing over the bowl and serve immediately.