1 tsp sugar 1/4 tsp salt 1/4 tsp bicarb of soda (baking soda)
Take 1 cup of unfed (discard) sourdough starter. Add the sugar, salt, and baking soda to the starter. The mixture should expand and bubble with the addition of the baking soda. If the batter does not react with the addition of the soda, you can add another 1/4 tsp.
You can use 4 x 9 cm diameter crumpet rings for the traditional crumpet or griddle them free-form (also known as pikelets). The free-form pikelets will be flatter and more pancake-like than the traditional crumpet, but the taste is the same.
Heat about 2 tbsps of butter on a griddle at medium-low heat. Add the batter (either to crumpet rings or free-form like a small pancake). Cook for a few minutes until the top is set and full of bubbles. Flip over and cook for an additional 2-3 minutes.