Combine salt and cornmeal. Add slowly to boiling water, stirring constantly to prevent lumps. Combine vinegar and milk; add 1 1/2 cup of milk mixture to cornmeal mixture; blend well.
Add eggs and melted shortening; stir to blend well. Dissolve baking soda in remaining 1/2 cup of vinegar and milk mixture. Add to cornmeal mixture and stir until completely blended. Pour into greased 1 1/2-quart casserole. Bake at 400° for 1 hour.
Serve immediately with a spoon.