- 1 small sweet onion, thinly sliced
- 2 pounds medium pickles, scrubbed, cut into 1/4-inch-thick rounds
- 1 large bunch dill, coarsely chopped (stems included)
- 1 tablespoon yellow mustard seeds
- 2 teaspoons whole white peppercorns
- 1 1/2 cups apple cider vinegar
- 1 cup water
- 1 cup sugar
- 3 tablespoons coarse kosher salt
- 2 teaspoons dill seeds
Divide sliced onion between two 1-quart wide-mouth glass jars. Pack cucumber slices horizontally in jars. Top each jar with dill.
Using mortar and pestle or resealable plastic bag and mallet, crush mustard seeds and peppercorns together. Place crushed spices in medium saucepan. Add vinegar, 1 cup water, sugar, coarse salt, and dill seeds. Bring mixture to boil over medium-high heat, stirring until sugar dissolves.
Ladle mixture evenly over cucumbers. Leave jars uncovered and chill 24 hours. Cover glass pickle jars tightly with lids. DO AHEAD: Can be made 1 week ahead. Keep refrigerated.