Again, another food I have never had. The closest I've ever come to turkey neck soup is watching a King Cobra feed on a turkey neck at the Cape Fear Serpentarium. (Apparently, the snake is fooled into thinking that the turkey neck is another snake and so it chomps it down for dinner.)
I can't find anything about the history of turkey neck soup, but it seems to be an American dish that came about to make sure no part of the turkey was wasted. Fabulous Foodie points out it must be an American dish, since the turkey is an American bird. (Sidenote: Benjamin Franklin pushed for the turkey to be the national bird of the USA.) Foodimentary seems to have gathered up all available information about turkey neck soup, which isn't a whole lot.
Looking around at recipes, it seems like you just make a stock using the turkey neck, then you toss in whatever vegetables you want. Want it kosher? Try this recipe from Joy of Kosher that uses lentils, barley, and mushrooms. This recipe from My Wooden Spoons is accompanied by a photographic record of the steps, but uses chicken neck. (I'm not sure if it still counts as turkey neck soup at that point.) Of the recipes I've found online, I think this one from Ingathered would be the one I'd follow. Why? It seems the least labor intensive and it uses wine.
I like recipes that use wine- they give me an excuse to buy wine without coming off as a lush.