though full of hard to source ingredients........
It's strange to hear you say that, Phil. I recently reviewed
The Book of Tapas here at Cheftalk,
http://www.cheftalk.com/products/the-book-of-tapas and found just the opposite. I was pleasantly surprised as the small percentage (there are, after all, 250 recipes) of the entries that called for hard to find ingredients. Frankly, I had expected more of them, considering this book is merely a translation from the Spanish, not one designed for the American marketplace.
Proportionately, I'd say a book like Batali's
Molto Gusto, supposedly aimed at American home cooks, calls for many more hard to source and impossible to find ingredients.
Like you, I'm in an area where "available in any supermarket" just doesn't apply. Most "specialty" ingredients have to be either ordered on line or substitutes found.
Because you used baby eels as an example, I just checked the entire cold-fish section. There are 35 recipes found there. Below is the total list of what I would consider hard to source ingredients. By that I mean not locally available (all of them are available on line). And some of them actually are available where I live, but I recognize that they might be difficult elsewhere. I've marked those with an asterisk:
Salmon roe, canned smoked eel*, elvers, salt cod*, crayfish*, mullet roe, octopus*, fresh sardines, smoked trout*.
So, in 35 "foreign" recipes we're talking about only 9 hard to find ingredients, many of which might actually be locally available if you search hard enough. Personally, I don't consider that to be a particularly high quantity.