I like to pound the chicken breasts with a meat tenderizer so they are all even in thickness. In a bowl, whisk together the smoked paprika, oregano, garlic powder, onion powder, a big pinch of salt and pepper and the crushed red pepper. Sprinkle it all over the chicken on both sides.
Heat the olive oil in a nonstick skillet over medium heat. Once hot, add the chicken and cook until deep in color on both sides - about 3 to 5 minutes per side. I like to use thin chicken breasts so the chicken is fully cooked in the skillet - to an internal temperature of 165 degrees F. You can also grill the chicken or bake it or cook it however is easiest for you!
Once the chicken is done, let it rest for 10 minutes. Then cut it into chunks.
In a bowl, toss the iceberg lettuce with a pinch of salt and pepper. Toss with the tomatoes, cucumber, avocado, red onion and feta. Add on the chicken. Drizzle with the vinaigrette and serve!