In a small bowl, combine sour cream and chipotle peppers.
Combine the rice mixture ingredients in a medium bowl. Season with a little salt and pepper. Set aside.
Season the salmon fillets with cumin, chili powder and salt and pepper. Drizzle them with olive oil.
Heat a grill pan over medium-high heat or heat a gas grill. Place the salmon fillets skin side up on the grill pan or grill and cook until nicely charred. Flip over and continue to cook until cooked through. Let cool some and then cut into pieces. Remove the skin if desired.
Drizzle the red onion slices with olive oil and season with salt and pepper. Grill until nicely charred on both sides. Note: If you have room, you can cook the onions at the same time as the salmon.
Warm the tortillas on the grill or grill pan.
In the center of each tortilla, pile some rice mixture, onions, salmon, avocado, cheese, and about 2 tablespoons of chipotle cream.Fold in the bottom and the sides and roll up.
Lightly brush the burritos with oil and heat in the grill pan or grill until crispy. Serve.