In a small bowl, combine the smoked paprika, garlic powder, onion powder, cayenne pepper, sea salt, and black pepper.
Pat the chicken breast dry with a paper towel and rub the spice mixture evenly over both sides.
Heat the olive oil in a cast-iron skillet or heavy pan over medium-high heat until shimmering.
Place the chicken in the skillet and sear for 5-7 minutes per side, or until the exterior is blackened and the internal temperature reaches 165°F.
While the chicken cooks, prepare the salad base by placing mixed greens, sliced cucumber, and halved cherry tomatoes in a large bowl.
Remove the chicken from the pan and let it rest for 5 minutes before slicing it into thin strips.
Top the greens with the sliced chicken and quartered avocado.
Drizzle the lemon juice over the salad as a light dressing and serve immediately.