Depending on the mold you use, you should get 12-14 crumpets from this batter.
The night before in a large bowl, add the starter and water. Mix well.
Add the flour and mix until fully combined.
Cover with plastic wrap or a plastic bowl cover and let ferment at room temperature for 8-12 hours.
The next morning, preheat a cast iron skillet or frying pan over medium-low heat.
Generously spray the rings with oil or brush with butter using a pastry brush.
Place in pan to preheat for 1-2 minutes.
Add the salt and baking soda to the crumpet batter.
Mix until combined and smooth.
Pour batter into the ring just below the top. I use a medium sized muffin scoop to add the batter.
Cook for 8-10 minutes checking the bottom periodically to make sure they are not over browning and adjust stove temperature as needed.
Crumpets are traditionally only cooked on one side.
You want to cook until the bubbles come to the top of the crumpet and until they are cooked through and are firm.
Remove the rings when the bubbles come to the top and tops are getting firm.
If you prefer your crumpets to be browned on both sides, turn them after removing the rings and brown.