Blot salmon with a paper towel, and lightly season skin and flesh with 1/2 tsp. salt. In a small bowl, combine maple syrup, Dijon mustard, curry powder, and remaining 1/4 tsp. salt; whisk to combine.
Heat oil in a large skillet over medium-high. Once hot, add fish, skin side-down, pressing firmly with a fish spatula to avoid the ends curling up. Cook 3 to 5 minutes, depending on thickness, until the flesh turns from translucent to opaque all the way up the sides.Turn off heat, gently flip the fish, and let the residual heat finish cooking the flesh side. Transfer fish to a plate and wipe skillet clean.
Return skillet to burner over medium heat and add butter. Once melted, whisk in maple-mustard mixture. Cook 2 minutes, stirring often, until mixture starts to bubble and thicken.Add salmon back to skillet; use a spoon to generously coat fish in maple-mustard glaze. Finish salmon with a squeeze of fresh lemon juice, and serve over grains with veggie of choice.
To Store. Place leftover salmon in an airtight storage container in the refrigerator for up to 2 days.To Reheat. Remove salmon from the fridge about 30 minutes before you plan on reheating it. Once you take the chill off, you can either reheat it in the oven, microwave, or a skillet. Whichever method you choose, be sure the reheating is gentle so the salmon doesn’t dry out.
Stovetop: Heat a skillet over medium-low, and rewarm individual salmon portions with a splash of water, covering the skillet. Remove the salmon once it is heated through (this should only take a couple of minutes).
Oven: Put the fish on a rimmed baking sheet and warm it a 275°F oven for about 15 minutes, until it reaches an internal temperature of 125°F to 130°F.
Microwave: Place your salmon on a microwave-safe plate, and set your microwave to 30 seconds. After 30 seconds, check the salmon and adjust it for even heating, and continue to microwave as needed.