In a mixing bowl, combine the warm water, sugar, and yeast. Stir gently and let it sit for about 10 minutes until frothy.
In another bowl, whisk together the flour, baking soda, and salt.
Gradually add the yeast mixture into the flour mixture, stirring until smooth and well combined. The batter will be quite thick but pourable.
Cover the bowl with a clean kitchen towel and allow the batter to rise in a warm place for about 20 minutes, or until slightly puffed.
Preheat your griddle or non-stick frying pan over medium-low heat. Lightly grease the crumpet rings and place them on the hot griddle.
Pour about 1/3 cup of the batter into each ring, filling them just to the top.
Cook the crumpets for about 5-7 minutes, or until the surface is bubbly and the edges set. They should not be flipped.
Once cooked, carefully remove the rings and flip the crumpets to cook the other side for an additional 2-3 minutes until golden brown.
Repeat the process with the remaining batter, greasing the rings as needed.
Serve the crumpets warm with your favorite toppings, such as butter, jam, or honey.