Lightly oil and line an 8×8-inch pan with parchment paper.
In a saucepan, bring juice to a simmer.
Mix sugar and pectin, then whisk into juice.
Boil until the mixture reaches 223°F.
Stir in lemon juice, then pour into prepared pan.
Let sit uncovered for 24–36 hours.
Cut into squares and roll in sugar before serving.
