Season the chicken breast evenly with garlic powder, half of the sea salt, and half of the black pepper.
Heat a non-stick skillet over medium-high heat and sear the chicken for 6-7 minutes per side until cooked through and golden brown.
While the chicken cooks, whisk together the olive oil, lemon juice, Dijon mustard, and the remaining salt and pepper in a small bowl to create the vinaigrette.
In a large salad bowl, combine the mixed baby greens with the fresh parsley, cilantro, and mint leaves.
Add the sliced cucumber and radishes to the greens and toss gently with half of the prepared vinaigrette.
Once the chicken is finished, let it rest for 3 minutes before slicing it into thin strips.
Top the salad with the sliced chicken and sunflower seeds, then drizzle with the remaining vinaigrette before serving.