In a small bowl, stir together the warm water, sugar and yeast. Leave to proof for 5-10 minutes. * see note 1
In a large mixing bowl, sift together the flour, baking soda and salt. Add the milk, vegan butter and yeast mixture. Stir until smooth. Cover the bowel with a tea towel and set it in a warm place to rise for 1 hour.
Lightly oil a heavy bottomed fry pan and heat over medium low heat. Lightly oil the crumpet rings. Spoon the batter into the rings until they're slightly over half way full and reduce the heat to the lowest setting.
Allow the crumpets to cook for 7-12 minutes (see note 2), or until the tops look dry. Remove the ring and flip the crumpets, cook for 30 seconds more or until the crumpets are firm.
Notes
The water should be warm to the touch, but not hot. If you have a thermometer, the water should be between 100-110 degrees. The yeast should get frothy and bubble up. If it doesn't, start over with fresh yeast.
The amount of time you'll need to cook your crumpets can vary depending on your stove. Be sure to keep the heat on the lowest setting, and do not flip them until holes have formed and the top is firm.