1. Combine buckwheat and all-purpose flours in a mixing bowl. Add buttermilk and yeast. Stir with a spoon until batter is smooth. Add more buttermilk, one tablespoon at a time, if batter is too stiff.

2. Cover the bowl with a dinner plate and let stand in a draft-free place, 8 hours to overnight.

3. Add sugar, baking soda, and salt after the overnight rest. Mix in enough hot water to give batter a thin, pourable consistency.

4. Heat a lightly oiled griddle over medium heat.

5. Drop batter by large spoonfuls onto the griddle and cook until bubbles appear and edges are dry, 3 to 4 minutes. Flip and cook until browned on the other side, 2 to 3 minutes. Reserve some batter as a starter for the next batch.

Cook's Notes:

After making desired number of pancakes, add enough buckwheat flour and buttermilk to make a batter. Cover and let stand in a draft-free place until more pancakes are to be made. Repeat steps 3 and 4 for each batch of pancakes, then make more batter each time following this step. Batter may be kept at room temperature and used repeatedly for 3 weeks. If any batter is left after 3 weeks, discard it.

Substitute 1 1/2 packets active dry yeast in 1 cup warm water if preferred.