Pat the chicken breast dry with paper towels and season it with salt, pepper, and half of the dried oregano. Let it rest for 5 minutes.

Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Add the seasoned chicken and sear for 5–6 minutes until golden brown. Flip and cook for an additional 3–4 minutes until cooked through. Transfer to a plate.

In the same skillet, add the remaining tablespoon of olive oil and sauté minced garlic for 30 seconds. Add diced red bell pepper and yellow squash, cooking for 4–5 minutes until softened.

Add halved cherry tomatoes and stir. Return the seared chicken to the pan, fold in fresh spinach, remaining oregano, and red pepper flakes. Sauté for 2–3 minutes until spinach wilts.

Remove from heat, zest a fresh lemon over the stir fry, and toss gently. Adjust seasoning and serve hot.