Heat the oven to 400 F.
In a medium bowl, toss the Brussels sprouts with 1 tablespoon olive oil, ¼ teaspoon kosher salt and black pepper until fully combined. Spread the seasoned Brussels sprouts across one half of a rimmed baking sheet.
In a medium bowl, toss the potatoes with 1 tablespoon olive oil and 1 teaspoon L&B Northern Lights Fish Seasoning. Spread the seasoned potatoes on the other half of the baking sheet.
Bake for 15 minutes, then remove from the oven. Flip the vegetables over and push them to the sides of the pan to create a space in the middle.
Pat the salmon fillets dry with paper towels. Drizzle both sides of the fillets with the remaining 1 tablespoon olive oil and season both sides with the remaining 4 teaspoons L&B Northern Lights Fish Seasoning. Place the salmon fillets in the middle of the pan, then place the butter slices on top of the fillets and return the sheet pan to the oven. Bake for 11 to 13 minutes, or until the salmon flakes and the thickest part of the salmon is cooked to an internal temperature of 145 F.
To make the Cilantro Cream Sauce: In a small bowl, combine the mayonnaise, sour cream, cilantro, lime juice, garlic and jalapeño. Season with kosher salt, mix well and set aside.
Serve the salmon, Brussels sprouts and potatoes hot with the Cilantro Cream Sauce.