Mash the butter and curry paste until well blended and smooth.
Preheat your grill to medium-high and sprinkle the trout with salt.
Grill for 4-5 minutes per side, until the thin edge flakes with a fork but the middle is still moist. (Alternatively, cook in a large skillet on the stove top, or roast in a 425˚F oven for 10 minutes.)
Serve topped with a dollop of curried butter and a squeeze of lime.