Rinse the quinoa thoroughly under cold water and cook with 0.5 cup of water in a small saucepan until fluffy and the liquid is absorbed.
Season the chicken breast evenly with half of the sea salt, black pepper, and dried oregano.
Heat a non-stick skillet over medium-high heat and cook the chicken for 6-7 minutes per side until the internal temperature reaches 165°F.
While the chicken and quinoa cool slightly, whisk together the olive oil, lemon juice, lemon zest, minced garlic, and the remaining salt, pepper, and oregano in a small jar.
Dice the cucumber into small cubes, halve the cherry tomatoes, and finely chop the fresh parsley.
Slice the cooked chicken breast into bite-sized pieces.
In a large mixing bowl, combine the cooked quinoa, chopped cucumber, cherry tomatoes, and parsley.
Add the sliced chicken and pour the lemon-herb dressing over the top, tossing everything together until well-coated.