Pat the chicken breast completely dry with paper towels to ensure a golden-brown crust.
Season both sides of the chicken evenly with sea salt, black pepper, and dried oregano.
Heat the olive oil in a stainless steel or cast-iron skillet over medium-high heat until shimmering.
Place the chicken in the pan and sear for 5-7 minutes per side until the internal temperature reaches 165°F and the exterior is crispy.
Remove the chicken from the pan and let it rest on a cutting board for 3 minutes.
In the same pan, reduce heat to medium and add the minced garlic, sautéing for 30 seconds until fragrant.
Add the baby spinach to the pan and toss briefly until just wilted, then stir in the lemon juice and lemon zest.
Fold the cooked quinoa into the greens until warmed through and coated in the pan juices.
Slice the chicken into strips and serve atop the bed of zesty greens and quinoa.