1. Place chicken fat in a large bowl, and add the egg yolks. Beat until thoroughly blended.
2. Add 3/4 cup matzo meal alternately with the hot water, 3 additions of each. Taste and add up to 1 teaspoon salt as desired. Stir in ginger.
3. Form a trial ball, about the diameter of a silver quarter in size. Drop into a pan of simmering water. Cover and cook for five minutes. It should hold its shape. If it crumbles, add a little more matzo meal (1 to 3 tablespoonfuls) and make another trial ball.
4. When consistency is satisfactory, chill matzo mixture for from 1 to 3 hours.
5. Then form into small balls and simmer for 15 to 20 minutes in a pan containing hot water or hot soup. For larger balls, use a longer period of time, up to 25 minutes.