You need a sourdough starter. Best to get some from someone. My partner Carina made ours about two years ago according to Dan Lepard’s recipe in his great book ‘The Handmade Loaf’. We keep it in the fridge. You can make crumpets with the starter straight from the fridge, but they do like it if you can let the starter warm up a little bit. The texture and crumpet-ness of the finished thing is entirely dependent on how loose/floury your starter is – hard to explain so best just to experiment.
Put 250/300g of starter in a bowl – or whatever amount you would usually remove to make a bread or refresh it. This should make one giant crumpet. This is the best way rather than pretending you only want a small one and using the ring, but up to you. You can always cut it up to share.
Add half a teaspoon of bicarbonate soda to the starter and stir through. Leave starter to sit and swell for a few minutes while you heat a large frying pan and melt a good click of salted butter in the pan so that the bottom and sides are completely covered. Pour in the starter – it will probably gather together in a big clump in the middle, but its best to stretch it out to the sides, reduce the heat a bit. Starter will start to form bubbles… try to get it so that its almost completely cooked before flipping it to finish off the top. Bottom should be crispy and a bit salty from the butter. Flip it onto a plate. Honey, cinnamon, greek yoghurt, fruit… done.