Looks great, though I agree with the commentards who think it would be better without avocado, cayenne and vinegar.
I'm intrigued that you chose to cook the muffins on a griddle. The closest thing to this I've ever heard of is oven-bottom muffins, but I don't think they're turned over, and their appearance suggests that they're mainly cooked by oven heat. I plan to try making griddled bread when I have the time.
I'm reasonably sure that the so-called English muffin didn't exist in England until about 30 years ago, when it started to appear in supermarkets. The fact that it's normally covered in cornmeal suggests foreign origins. It used to be nearly impossible to buy cornmeal, even in London - you had to find a shop that carried imported American foods for expatriates. I don't think anyone knew that it was the same as polenta.
Admittedly "muffin" is a fairly ambiguous name. Britain seems to have an endless regional variety of names for small cakes of bread (bap, barm cake, plain teacake...).