By Jayne Cohen
In a strainer, toss the onions with the salt. Cover them with a paper towel and weight down with a bowl or plate topped with a heavy object like a large can of tomatoes. Let the onions drain for at least 30 minutes, tossing them occasionally. Place the onions in fresh paper toweling or a clean kitchen towel, and squeeze out as much liquid as possible.
Warm the oil in a