Soak freshly picked cucumbers in a tub of ice water overnight. Remove and dry the cucumbers, then pack them into sterilized jars along with the garlic cloves, dill sprig, and peppercorns. In a large pot over medium-high heat, bring 2 quarts of water to a boil. Add the vinegar and salt and boil for 5 minutes. Pour the hot brine over the cucumbers, leaving 1⁄4 inch of headroom. Wipe dry the rims of the jars, then cap each with a lid and screw band. Prepare a boiling water bath and process the jars in it for 10 minutes. Remove the jars from the bath and set them on a towel on the counter. They will “seal” during the cooling-off process. Place any jars that do not seal properly in the refrigerator and use first.