1-1/2 cups white sugar
1/4 cup boiling water
Use a vegetable peeler (Y-shaped recommended) to remove the outermost part of the lemon peels, leaving behind as much of the white pith as possible.
Place zests in a large mixing bowl. Add sugar and knead together until the zests are well coated.
Allow mixture to sit at room temperature for at least an hour (no longer than overnight). The sugar will extract the aromatic oils from the lemon zest and dissolve into a rich, fragrant syrup. This is the oleo saccharum.
Pour boiling water over the mixture to capture any undissolved sugar and any oleo saccharum stuck to the zests.
Strain and employ in a punch or cocktail, or forego the straining and add mixture, peels and all, for a more rustic punch experience.
Note: Orange and grapefruit zest can also be used. If you choose to use these, you'll need to adjust the ratio of fruit to sugar. Here are some ratios that will work. Don't worry; punchmaking is an art, but not an exacting one.
Zest of 1 lemon : 2 fluid oz. sugar
Zest of 1 orange : 3 fluid oz. sugar
Zest of 1 grapefruit : 4 fluid oz. sugar