Pickled Green Tomatoes with Mixed Peppercorns

• 1 Tbsp rainbow peppercorns
• ½ cup [120 ml] rice wine vinegar

With a mortar and pestle, lightly crack the peppercorns. Transfer to a small, nonreactive saucepan and add the vinegar, mirin, salt, sugar, and long pepper. Bring to a boil over medium-high heat. Remove from the heat and cool completely. Fish out the peppercorns, leaving the liquid in the saucepan, and set aside.

Remove the stems from the tomatoes and, using a sharp paring knife, cut th