Preheat oven to 400 degrees. Line a baking sheet with aluminum foil.
Place halibut on the foil. Season both sides of the fish with kosher salt to taste and cumin. Combine butter and lime juice in a small bowl and drizzle over the fillets.

Put corn chips in a sealable plastic bag and crush into small pieces using the palm of your hand, which should yield about 1/4 cup. Top each fillet with a thick layer of crumbs. Cover loosely with aluminum foil to prevent excess browning. Bake 10 minutes and remove the foil. Continue to bake another 10 minutes or until fish is opaque in color.

Whisk together the salsa and sour cream in a small saucepan over low heat. Heat until just warmed through, 2 to 3 minutes.
Place each halibut fillet on a plate, top with creamy salsa and garnish with cilantro leaves.