Preheat the oven to 400°F. Grease the wells of a 12-cup muffin pan, or line with papers and grease the insides of the papers., In a large saucepan, combine the water, dates, sugar, butter, and vanilla. Cook over medium heat and bring to a boil, stirring often., Remove from the heat and stir in the cranberries, nuts, baking soda, salt, and eggs; mix thoroughly. Stir in the starter and the flour until evenly combined., Scoop the batter by the quarter-cupful into the prepared pan. Bake the muffins for 17 to 19 minutes, until a paring knife inserted in the center of one comes out clean., Remove the muffins from the oven and cool them in the pan for 5 minutes before transferring them to a rack to cool completely., Store any leftover muffins, tightly wrapped in plastic, at room temperature for several days; freeze for longer storage.