Place the parsley and 3 cups cold water in a saucepan. Bring to a boil, cover, reduce heat, and summer for 1 minute. Set aside for 30 minutes. Uncover, and when cool enough to handle, squeeze the parsley over the pot, then discard it. Pour Parsley Elixir into a pitcher and chill.
Add to chilled Parsley Elixir the lemon juice, ginger, and sweetener to taste. Fill 4 tall glasses with ice, and pour in Parsley Ginger Lemonade. Garnish with the lemon slices.
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