Pour white wine, cream, and coconut milk into a saucepan; season with curry powder. Bring to a light boil over medium-high heat, then reduce heat to medium-low, and simmer until the liquid has reduced to 1/2 cup, about 10 minutes.
When the liquid has reduced, turn heat to low, and whisk in the butter, a few cubes at a time, until all of the butter has incorporated. Do not allow the mixture to boil or else it will separate. When the butter has incorporated, season to taste with salt and set aside to keep warm.
Heat the oil in a saute pan over medium-high heat until it begins to smoke. While the oil is heating, lightly season both sides of the salmon with garam masala and salt.
Sear the salmon in the hot oil for 3 to 4 minutes on one side, then turn over, and continue cooking for 2 to 3 minutes until done. Briefly drain on paper towels to absorb excess oil, then serve immediately with the curry butter sauce.