Overnight Refrigerator Pickles

I got this recipe from our CSA discussion board. We got seven cucumbers last week and there was no way we could eat all of them and since we also got a ton of dill over the last few weeks from them pickles seemed like a natural choice. I ended up using a mix of apple cider, white, and balsamic vinegars because I didn't have enough of any one kind. I also substituted ground mustard and ground pepper for the seeds and fresh dill for the dill seeds. They turned out a lot like bread and butter pickles if you've ever had those. They were great on a ham and cheese sandwich.

Slightly Sweet Dill Refrigerator Pickles

1 small sweet onion (such as Vidalia or Maui), thinly sliced
2 pounds medium pickling cucumbers, 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.