Combine 2 quarts water and the salt in a large pot and bring to a boil over high heat. Add the basil and blanch 15 seconds, or until it is bright green and wilted; immediately plunge it into a bowl of ice water. Drain the basil, wrap it in a kitchen towel, and gently squeeze out as much water as possible. In a blender, combine the basil with the oil and blend until smooth. Strain through a cheesecloth-lined sieve, without pressing down on the solids.