Add in buttermilk, melted butter, eggs and vanilla, and mix until well blended. Add in cold water gradually (1 tbsp at a time), until you have a slightly thick but still pourable batter (discard extra water). Pour about 1/3 cup of batter (adjust the amount according to your waffle machine) in the middle of the preheated waffle iron, cover and cook until the waffle is lightly browned on both sides. Repeat the same process for the remaining batter. Serve warm on its own or with sugar-free syrup (or with fruits for Phase 3), if desired.