Remove 1 cup of the cream that has risen to the top of the chilled coconut milk and add to a large skillet or wok. Bring to a boil and cook for 5-8 minutes until the oil begins to separate from the white solids. Add curry paste and continue to cook for another 5-8 minutes. Add some thin coconut milk a little at a time if the mixture begins to stick.
Meanwhile, combine the thin coconut milk remaining in the can the cream was removed from with ½ cup of well stirred milk from the second can. Reserve the remaining milk from the second can for a later use. Add ½ cup of water.
Add salmon pieces to the skillet with the curry paste and coconut cream. Stir-fry for 2 minutes. Add the remaining thin coconut milk and let simmer, turning occasionally until the salmon is cooked through.
Stir in fish sauce, brown sugar, limejuice, and red pepper slices, mushrooms, fresh basil and simmer for another 2 to 3 minutes.