Put all but 1 cup cranberries in a saucepan. Add the lime juice, sugar, cumin, a pinch of salt, the jalapenos and brine and 1/4 cup water. Bring to a simmer over medium heat; cook, stirring occasionally, until the berries burst and the sauce thickens, 15 to 20 minutes.
Stir in the remaining 1 cup cranberries and cook until softened, 3 to 4 minutes. Remove from the heat and stir in the lime zest. Let cool, then transfer to a serving dish and refrigerate at least 3 hours.