How to Make It
Combine brown sugar, water, peppercorns, cinnamon sticks, allspice berries, cloves, and crushed cardamom pod in a saucepan over medium-high; bring to a boil, stirring until sugar dissolves. Remove from heat; steep 1 hour. Strain syrup; discard solids. Cool completely. Stir 1 1/2 Tbsp. syrup into 1 cup (or more, depending on desired flavor) seltzer water. Store syrup chilled up to 2 weeks.