A crumpet is an English griddle bread - something between a pancake and an English muffin. Plop goes the bubbly batter, fizz goes the fragrant cooking. Use a cast iron griddle, an electric griddle, or a large skillet. Crumpet rings, like English Muffin rings, are entirely superfluous.
Most recipes call for baking soda, which is added near the end of the batter's rest time.
In a large bowl, or in the bowl of an electric mixer, stir together water and yeast. Let stand a few minutes. Stir to encourage batter to become slightly elastic. Do not add too much flour. This should be more batter than dough.