Preheat a heavy duty or iron pan over medium heat. Rub or brush with oil. Prepare crumpet rings by greasing with oil and place on the pan to preheat.

Whisk together all of the ingredients EXCEPT for the white vinegar. Whisk vigorously for 2-3 minutes until the gluten feels somewhat strengthened.

By this time, the pan should have preheated for around 5 minutes. If you have a thermometer, measure the temperature of the pan. It should be around 150 degrees C. If it is not at temperature yet, wait until it reaches close to 150 C before proceeding to the next step.

Pour the vinegar into the batter all at once. Working quickly, whisk to thoroughly combine. The batter will bubble up immediately.

Pour the batter into the preheated crumpet rings. There should be around 1 cm of batter in each ring, but the batter will rise immediately. The crumpet rings should be 1/3 to ½ filled when the batter is initially poured in. Do not overfill or the batter may overflow. The batter will bubble up and holes will start appearing within a minute.

The tops of the crumpets should be full of holes. If it is not, see the troubleshooting section above. Lower the heat if the bottoms of the crumpets get too dark. Remove the crumpet rings once the edges of the crumpets are cooked and dry. The rings should be easy to remove. If the rings were adequately greased, the edges of the crumpets should shrink away from the rings as they cook.

Cook over medium heat until the tops of the crumpets are dry. Lower the heat if the bottoms of the crumpets get too dark.

Flip the crumpets over and toast the other side lightly (30 seconds) or if desired, for longer until golden.

Enjoy warm with butter or let cool before putting away. These crumpets will continue to be soft the following day at room temperature and can also be reheated in the toaster if desired.