Infusions
Combine the vermouth and zest in an iSi whipper. Seal tightly. Charge with an N2O cartridge, then shake the canister about five times. Change the cartridge, then charge and shake again. Let stand for 15 minutes, shaking the canister every 30 seconds or so, then release the pressure. Point the canister’s nozzle at a 45-degree angle into a container. Vent the gas as quickly as possible without spraying liquid everywhere; the quicker the venting, the better the infusion. When all of the gas is out, open the canister and take a listen. Once there is no longer audible bubbling, open the canister and strain the infusion through a paper coffee filter or Superbag. Funnel back into the vermouth bottle and refrigerate until ready to use, up to 4 weeks.