In a small pot, combine the dry quinoa with 0.5 cup of water and a pinch of salt. Bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes until fluffy.
While quinoa cooks, slice the chicken breast into bite-sized pieces and season with garlic powder, half of the sea salt, and half of the black pepper.
Heat 0.5 tbsp of olive oil in a skillet over medium-high heat. Add the chicken and sauté for 6-8 minutes until golden brown and cooked through.
In a small jar or bowl, whisk together the remaining 0.5 tbsp of olive oil, apple cider vinegar, lemon juice, dried oregano, and the remaining salt and pepper to create a tangy vinaigrette.
Dice the cucumber, halve the cherry tomatoes, and finely mince the red onion.
In a large bowl, layer the baby spinach and cooked quinoa. Top with the sautéed chicken, cucumber, tomatoes, red onion, and sliced avocado.
Drizzle the tangy vinaigrette over the bowl and toss gently before serving to ensure every bite is coated in the bright, herbaceous dressing.