Pour 1 1/2 cups boiling water over liver.
Drain, reserving water.
Remove tough outer membrane from liver.
Dry meat and dredge with the flour.
Brown on all sides in 4 tablespoons of the fat.
Add reserved water and 1/4 teaspoon salt.
Cover and simmer for 1 1/2 hours, or until tender.
Cook onions in remaining fat for 2 or 3 minutes.
Add remaining salt, 1 cup water, and remaining ingredients.
Bring to boil, cover, and simmer for 45 minutes.
Slice liver and serve with the sauce.