In a large bowl, combine brown sugar, kosher salt, black pepper, maple syrup, and soy sauce. Mix well.
Place the salmon fillets, skin-side down, on a wire rack.
Rub the dry brine mixture on the top of the fillets, making sure to cover them evenly.
Wrap the fillets with plastic wrap and refrigerate for 8-12 hours.
Remove the fillets from the refrigerator and rinse them off under cold water. Pat dry with paper towels.
Place the fillets, skin-side down, on the wire rack.
Place the wood chips in the wood chip tray of the Masterbuilt electric smoker.
Preheat the smoker to 200°F.
Once preheated, place the wire rack with the fillets on the bottom rack of the smoker.
Smoke the salmon for 2-3 hours, or until the internal temperature reaches 145°F.
Remove the fillets from the smoker and let them cool on a cooling rack.
Once cooled, use a sharp knife to remove any remaining pin bones from the fillets.
Serve with lemon slices and a drizzle of olive oil.