Heat the olive oil in an OVENPROOF large skillet over medium-high heat.
Season each side of the chicken breasts with sea salt, freshly cracked pepper, oregano, and garlic powder, to taste.
Place the chicken in the HOT skillet and cook for 4 minutes, until golden brown. Flip and continue cooking for 4 minutes.
Place the OVENPROOF large skillet in the oven and bake for 10 minutes or until the chicken has cooked through.
Remove from the oven and place on a cutting board to rest for 5 minutes before slicing into bite-size pieces.
Make the salad by placing the lettuce in a large bowl and topping it with bell pepper, pepperoncini slices, kalamata olives, feta cheese, homemade croutons, and sliced chicken.
Drizzle some of the well-whisked vinaigrette on top, to taste, and toss to coat evenly.