Step 1

Thinly slice the onions (it's helpful to use a mandoline), and divide the onions between 2 (16-ounce) jars or equivalent. Place the garlic and peppercorns in each jar, if using

Step 2

Heat the vinegar, water, sugar, and salt in a medium saucepan over medium heat. Stir until the sugar and salt dissolve, about 1 minute. Let cool and pour over the onions. Set aside to cool to room temperature, then store the onions in the fridge.

Step 3

Your pickled onions will be ready to eat once they're bright pink and tender - about 1 hour for very thinly sliced onions, or overnight for thicker sliced onions.