Place all ingredients in a medium-sized saucepan.
Bring to a boil and stir until everything is well-integrated and sugar is dissolved.
Continue to boil for another 3-4 minutes, until the cranberry skins start to burst.
Reduce heat to low and simmer for another 15-20 minutes, or until reduced and thickened, stirring occasionally.
Remove from heat and cool completely. Sauce will thicken as it cooled. Store in an airtight container until ready to serve! Then garnish with finely diced jalapeños.