Strip the zest from 12 limes, reserving the zest, then juice the limes. Weigh the lime juice and measure an equal amount of sugar (by weight). In a nonreactive container, combine the lime juice and sugar and stir until the sugar is dissolved. Stir in the lime zest and taste; the mixture should be slightly more tart than sweet and fairly viscous. Adjust the flavor and texture as needed with more lime juice or sugar. Cover and let stand at room temperature for 24 hours, stirring occasionally. Strain through a fine-mesh sieve. Store in the refrigerator for up to 1 month.
— Death & Co.