Since a lot of the responses to the canning post below requested pictures, below is step-by-step with pictures of how we've been canning cucumber-onion salad this summer. This is a great side dish for grilled chicken or steak, and I can't wait to eat our jars in the winter. This takes about 1 1/2 hours start-to-finish.
Fresh-Pack Cucumber-Onion Salad
There is no quantity of pickles given as this method may be used for several quarts/pints of salad. The amount of brine given is sufficient for about six quarts of salad. Larger or smaller amounts of brine may be prepared, but be sure to keep the correct proportions of water, salt, and vinegar intact. Use pickling cucumbers that are 2-1/3 to 3 inches in length. The last time we did this, 6 pounds of cucumbers and 3 pounds of onions yielded 7 pints of salad.
1.) Wash and peel the cucumbers carefully. I find a carrot peeler works best for this. Slice onions into 1/2" thick slices, slice cucumbers into 1/4" slices.
2.) Bring brine contents to a boil.
3.) Prepare canning jars and lids according to canning directions, we use the Ball Blue Book Guide to Preserving
4.) Removing one jar at a time from wherever you've sterilized them (dishwasher or boiling water on stovetop), pack jars alternating layers of cucumbers and onions. Cover mixture with boiling hot brine, leaving 1/2" headspace. Wipe rim of jar. Remove lid from water, place lid on jar and screw on metal band to fingertip tight (just to the point of resistance). Do not overtighten band.
5.) Add jars to boiling-water bath canner and process Pints 15 minutes, Quarts 20 minutes. Count processing time when water returns to a boil.
6.) Remove jars. Do not tighten screw bands. Set jars upright several inches apart to cool for 24 hours. Listen for rewarding "ping" sound the jars make when they seal.
7.) After jars have rested for 24 hours, check to make sure they sealed by removing bands and lifting jar by the lid. Dispose of any unsealed jars. Wipe jars clean and store in a cool, dry, dark place.