Add the fish sauce, white sugar, brown sugar, water and pepper, and bring to a boil. Cook until the sugar has dissolved and the sauce has thickened, about 2-3 minutes.
Add the salmon to the skillet, in a single layer. Allow space between each piece of salmon. Cover and simmer the salmon in the sauce for 10 minutes. Flip the salmon and cook for another 5 minutes.
Transfer the salmon to a bowl and spoon some of the sauce over each piece of salmon. Serve hot with your favorite side, such as rice.
Recipe by The Little Chef at http://littlechefblog.com/ca-kho-to/