Pat chicken breasts dry and season both sides with salt and pepper.
Combine honey and red pepper flakes in a small microwave-safe bowl; heat for 30 seconds to infuse.
Heat olive oil in a large skillet over medium-high heat.
Place chicken in the skillet and cook for 6 to 7 minutes per side until the internal temperature reaches 165°F (74°C).
During the final 2 minutes of cooking, brush 2 tablespoons of the hot honey mixture over the chicken breasts to glaze.
Transfer chicken to a cutting board and allow to rest for 5 minutes before slicing into strips.
Whisk the remaining hot honey with apple cider vinegar to create the dressing.
In a large bowl, combine greens, tomatoes, cucumber, and onion.
Arrange sliced chicken over the salad base and garnish with sunflower seeds.
Drizzle the prepared dressing over the salad and serve immediately.