Pour the melted fat into a small cast iron skillet. Place the salmon fillets in the skillet and add enough water to cover the fillets. Season the poaching liquid with the salt.
2
Heat on medium-low until the poaching liquid is steaming but not boiling (about 165°F). Poach the fillets until the fish is cooked through and opaque, 10 to 12 minutes (depending on how thick your fillets are). Remove the salmon from the poaching liquid.
3
Serve each piece of fish with 2 tablespoons of mayo if desired.
4
Store leftover salmon and dill sauce separately in airtight containers in the fridge for up to 3 days. To reheat, place the salmon in a heat-safe dish with a few tablespoons of water, cover, and place in a preheated 350°F oven until warmed.