Check out the recipe below including the description & the comments on the side.

Here is a link that might be useful: Pickled onions

Thanks Ginger, that looks like the pickled onions I've been searching for. I remember they weren't sweet at all, so thanks also for the heads up regarding the comment along the side... I too will omit the sugar.

Hope it turns out to really be the same. Glad to help.

Here are a couple of different recipes. I usually pickle smaller onions, such as Pearls and Rakkyo. But they are ok to use with larger ones.

The first has no sugar, and might be more like the ones you had in Maryland:

Pickled Onions

2 lbs white onions
4 cups water
1/2 cup salt
1 at malt vinegar
2 tbls pickling spices
4 cloves
2 bay leaves

Peel the onions. Heat the water and salt to the boilin g point. Pour the salted water over the onions and let soak 12 hours.

Place the vinegar, pickling spices, cloves and bay leaves in a saucepan. Cover and simmer for ten minutes. Drain the onions and add to the pan. Cook, uncovered, 15 minutes. The onions should remain firm and crunchy.

Transfer the onions to hot sterilized jars. Pour the vinegar over the onions, adjust lids, and process pints in a boiling water bath 10 minutes. Wait at least a month before sampling the onions.

This next is slightly sweeter, and comes from the Ball Blue Book:

Onion Pickles

4 quarts peeled pearl onions
1 cup canning salt
2 cups sugar
1/4 cup mustard seed
2 1/2 tbls prepared horseradish
2 quarts vinegar
7 small hot red peppers
7 bay leaves

Sprinkle onions with salt; add cold water to cover. Let stand 18 hours. Drain; rinse and drain thoroughly.

Combine sugar, mustard seed, horseradish and vinegar in a large saucepot. Simmer 15 minutes.

Pack onions into hot jars, leaving 1/4 inch headspace. Cuty two small slits in hot peppers. Add 1 pepper and 1 bay leaf to each pint jar. Ladle hot liquid over onions, leaving 1/4 inch headspace. Remove air bubbles. Adjust lids. Process half-pints and pints 10 minutes in boiling water canner.

Recipe variation: For sour onions pickles omit all or part of sugar and bay leaves.