Preheat the grill or a grill pan over medium-high heat. In a small bowl, mix together the olive oil, chili powder, cumin, garlic powder, salt, and black pepper. Brush the mixture onto both sides of the salmon fillets.
Grill the salmon for about 4-5 minutes on each side, or until the fish flakes easily with a fork. Remove from the grill and let it rest for a few minutes.
While the salmon is resting, prepare the salad. In a large bowl, combine the mixed salad greens, cherry tomatoes, corn, avocado, black beans, red onion, and cilantro.
Flake the grilled salmon into bite-sized pieces and add it to the salad.
Drizzle the lime juice over the salad and toss gently to combine. If desired, add ranch dressing for extra creaminess.
Serve immediately, or chill in the refrigerator for up to 30 minutes before serving for a refreshing option.