Beat the egg whites until frothy with the salt, add the yolks and beat some more. Add just enough matza meal to make small balls with wet hands--work fast! Drop them into boiling water as soon as they're shaped, or they'll turn into rocks. Cover and cook on medium about 30 minutes. You can make these hours ahead; after they're cooked, drain and put them in the pot of soup you have ready and heat together when ready to serve.