Combine sourdough starter, flour, and water in a mixing bowl or jug.
Cover and leave to rest in a warm place for at least 3 hours (overnight if you prefer).
Stir down the risen dough.
Add the eggs and the baking soda and stir to combine.
(If making banana sourdough pancakes, add mashed banana here).
Melt butter in frying pan or griddle and add circles of mixture.
Once large bubbles appear on the surface, flip the pancakes.
Remove from heat once cooked and serve.