From 1918:
Soak four matzoth in cold water and press them after being thoroughly saturated. Add a little pepper, salt, sugar, parsley, and a half onion chopped fine, first browning the onion. Beat four eggs and add all together. Then put in enough matzoh meal so that it may be rolled into balls. The less meal used the lighter will be the balls. They should boil for twenty minutes before serving. Serve matzoth kleis in place of potatoes and garnish with minced onions browned in three tablespoons of fat.
All matzoth meal and matzoth kleis are lighter if made a few hours before required and put in the ice-chest until ready to boil. When used as a vegetable make the balls considerably larger than for soup.