1 teaspoon salt
Oil a bowl, add the dough, cover and let it rise. In the meantime, drain the ginger but save the water. Add the ginger, 2 tablespoons of soaking water and 2 tablespoons sugar to a blender, and purée the mixture. Stir in a teaspoon vanilla.
Take four tablespoons of water, 4 tablespoons of sugar, two tablespoons of soaking water and 4 tablespoons butter and put it on the stove in a small saucepan. Bring it slowly to a boil, then let it simmer for ten minutes until you have a buttery syrup. Set aside to cool. The syrup will thicken as it cools.
Punch down the dough, and divide into 12 equal parts.
Mix four tablespoons sugar with one teaspoon cinnamon. Sprinkle a teaspoon on your countertop. Roll each piece of dough into a small ball, then roll it out into a rectangle on top of the sugar. Put a line of ginger purée in the middle of the dough, lengthwise, and fold the dough over to the top. Fold one more time, pinch the seams and carefully roll the dough in the sugar. Now take one side of the dough and roll it, roly-poly wise, onto itself. Tuck in the end piece. Do this with all the pieces of dough.
Turn on the oven to 350F. Brush the inside of the aluminum cups (or a muffin pan) with the syrup, and place each gemberbolus in a cup. You can put a little bit of ginger purée in the middle, if you wish. Cover the rolls and let them rest for about fifteen minutes while the oven heats up.
Brush the rolls with more syrup when they come out of the oven, and let them cool. Eat warm, cold or heated up.