Preheat the broiler: set your oven to broil on high and position a rack 6 inches from the top. Line a rimmed baking sheet with foil, parchment paper and/or lightly grease with cooking spray. Let the broiler preheat for at least 5 minutes (I like 10 minutes).
Make the blackening spice rub: In a small bowl, combine smoked paprika, garlic powder, cumin, chili powder, cayenne pepper, and salt. Pat the salmon fillets completely dry with paper towels. Brush 1 tbsp olive oil over the fillets and rub to coat, then press the spice blend generously over the top and sides of each fillet.
Arrange the sheet pan dinner: place the salmon (skin side down) on one side of the sheet pan, and the broccolini on the other. Brush the broccolini with the remaining olive oil and sprinkle with salt, pepper, and garlic powder
Broil: transfer the sheet pan to the oven and broil for 8 - 10 minutes (depending on oven). My oven is hot and took right around 8 minutes. You can begin checking at the 7 minute market. The tops of the salmon should be charred and caramelized. No flipping needed!
While the salmon is cooking, make the pesto. Add olive oil, cilantro, avocado, jalapeno (if using), garlic, lime juice, salt, and water to a food processor. Blend until smooth and creamy, about 1 minute. You may need to stop and scrape along the sides with a spatula. Add in water as needed to get the desired consistency.
Assemble and serve: Divide the rice into 4 bowls. Place a piece of salmon on top, along with the broccolini. Top with cilantro avocado pesto and lime wedges (if using).