Generously grease twelve 2-1/2-inch muffin pans. Set aside. Dissolve baking soda in hot water.
In a large bowl, stir together flour, molasses, and soda-water mixture until smooth. Fold in cranberries. Fill prepared pans about two-thirds to three-fourths full of batter.
Bake in a 350 degree F oven for about 25 minutes or until a toothpick inserted near the center of one pudding comes out clean. Cool slightly. Remove from pans.
Serve puddings warm with warm Vanilla Sauce. Makes 12 servings.