Don't worry about derailing, FF, that's what's so nice about these forums.
My comment on omelette-wrapped fish was a joke, BDL (as i think you know) and Pohaku - though i don;t much like omelettes that are not creamy, and don't much like egg on my fish in general. ( I prefer cheese 
) (not to bring up THAT discussion again!)
I agree with FF that an explanation is worth a hundred recipes. For which we have some good explainers here. I do read lots of cookbooks, and the good ones do explain things. Yes to julia child, no to joy of cooking, (i rarely use joy of cooking, due to the lack of explanations). Yes to the time life series for the most part, and to many other little-known cookbooks. . And if you tell me to start my potatoes in cold water, you'd dxxxn well better tell me why or i will never do it. I never have that much time anyway, so I probably won't do it anyway, and will cut my potatoes up to make them cook faster. (then the "insides" will be outside and will cook at the same time as the outside!)
Anyway, about the thin and crispy batter and the thicker and more dense batter, i have another question
Why do some batter recipes call for beaten egg whites or baking powder, when my experience with these is that they create a spongelike texture for the batter which acts exactly like that, like a sponge, and gives me soggy and greasy fried food.
I use egg with a little water in it as a way to coat the food to protect it from absorbing fat (egg cooks quickly if it's thinly coating the food so, i presume, seals out the oil), and it also helps stick bread crumbs so they don;t fall off. If i want the crust a little more substantial i use flour under the egg.
If i want a very thin crisp crust, i coat in thick greek yoghurt and then flour. It tenderizes the food under it and makes a wonderful crispy crust that stays crispy. If i want to make a nice thick batter that gets crisp, i mix egg and yoghurt and flour, and then roll in bread crumbs.
But while i get good results frying (and i don;t have a deep frier, just a frying pan - i put a good amount of oil in it and just fry a few things at a time, trying to keep the oil to a point of vigorously sizzling the food as it drops in but not burning) - i ALWAYS got lousy sodden results when adding any sort of bubble-making substance, beaten eggwhites or baking powder. For me it's a recipe for disaster and I don't understand if i'm doing something wrong or it's the leavening itself that's wrong.
And again, the oil. I still don't fully understand - tighter and richer crust, you say, BDL. closer to the food you say. Better done by drying the food first. Yes, for sure. Even flouring it, perhaps. Richer crust? maybe egg would be a richer crust. I'm thinking of the sodden fish filets in that egg and oil omelette "crust" - not appealing. But i;ve also seen oil in other eggless batters.
tell me more. Why, why, WHY....
