Pat salmon fillets completely dry with paper towels. In a small bowl, mix together chili powder, cumin, smoked paprika, garlic powder, onion powder, salt, and pepper. Rub the spice mixture over the flesh side of each salmon fillet.
Heat olive oil in a large skillet with a lid over medium-high heat. Place salmon skin-side up and sear for 3-4 minutes until a dark crust forms. Flip and cook for 2 more minutes. Remove salmon to a plate.
Reduce heat to medium. Add the chopped onion to the same skillet and sauté for 3-4 minutes until soft. Add minced garlic and cook for 1 minute until fragrant.
Add the rinsed rice to the skillet and stir for 1-2 minutes to toast. Pour in the broth, then stir in the black beans and corn. Bring to a simmer.
Nestle the salmon fillets on top of the rice mixture, skin-side down. Reduce heat to low, cover, and cook for 15 minutes without lifting the lid.
Turn off the heat and let the skillet stand, covered, for another 5-10 minutes. Uncover, fluff the rice with a fork, and serve immediately with fresh cilantro, avocado, and lime wedges.
Notes
For the best results, use a heavy-bottomed skillet with a tight-fitting lid to ensure even cooking and prevent steam from escaping.