Combine: Mix the dry ingredients in a large bowl.
Activate: If using dried yeast, whisk it into a small portion of your warm water/milk mix and let it sit for 5–10 minutes until frothy.
Mix: Combine the wet and dry ingredients. Whisk until smooth (it should be the consistency of thin, frothy double cream).
Proof: Cover and leave in a warm place for about 1 hour until bubbly, or—for a deeper, more traditional fermented flavour—leave it in the fridge overnight.
Cook: Heat a heavy-bottomed, non-stick frying pan (or a griddle/baking stone if you have one) over a medium-high heat. Lightly grease with a little lard or bacon fat.
Ladle: Pour in a ladleful of batter. Swirl the pan to ensure an even, thin layer (about 2-3mm). The "Lace": Cook until the surface is dry and covered in small, "lacy" pockmarks.
Flip: Carefully turn the oatcake over and cook for another minute until golden.
Serve: Traditionally, place a handful of grated mature cheddar and some cooked bacon on one half, fold it over, and let the residual heat melt the cheese before serving.