First, let's make an Oleo Saccharum (a citrus oil syrup):
Using a vegetable peeler, remove the peel from 3 lemons, trying to remove as little pith as possible. Juice the lemons, and set the juice aside for a moment.
Combine the peels with 110g (½ cup) sugar in a bowl. Toss the peels to completely cover them with the sugar, rubbing them to help begin releasing the peels' essential oils.
Inside the Porthole:
- Transfer the Oleo Saccharum mixture to the Porthole.
- Close the Porthole, checking the seal for good contact on both sides.
- Let sit for 1 hour or more, occasionally shaking (with stopper inserted).
Liquid to be Added:
- 113g (½ cup) rice wine vinegar
- 160g (¾ cup, about 3 lemons' worth) lemon juice, strained to remove pulp
- 113g (½ cup) sake