Remove the zest from the lemons. Cut away the white pith and discard. Finely chop the lemon zest and pulp. Mix lemon with salt. Let mixture stand overnight in a 2-quart stainless steel saucepan. Next day, add remaining ingredients. Cook mixture gently, stirring, until thickened, 45 minutes to an hour. Pour into clean pint jars and refrigerate. Let rest about a month before serving. Makes 2 pints.