As far as I know, salted green onions were used as an ingredient by the French in northern Maine. My grandmother used to put this into many of her dishes, mainly soups.
Clean and chop the onions, and place them into a sealable jar. I like to cut them into 1-2" pieces.
Add enough of the salt to thickly coat all of the onions. You cannot use too much, but try not to bury them.
Seal jar and set leave in kitchen for 3 days, shaking jar once a day.
You should see water collecting from the onions. This is normal.
Drain onions in a collander, and place back into jar.
Add more salt to replace what was lost in the draining.
Seal jar and keep in refridgerator.
These onions will last for several months.
Before you use the onions, rinse them lightly in a collander. The onions are very salty and will dissolve in soups and other long cooking dishes. Beware that it is easy to over salt the dish. But, you'll be surprised at the flavor that they can bring.