I believe this topic has surfaced a few times over the years. I know that our friend Victor de la Serna posted on the subject in the old FLDG forum. in that post he had some words of advice (or so I took them). I don't think he would mind these word resurfacing here. He also posted a recipe (not his) for an authentic paella. I will italicize the part of this post that is Victors. I will follow this post with the recipe that Victor posted in the original FLDG.
"Real" Paella Valenciana and more
The paella, i.e. the recipient not the recipe, is crucial. It has to be
thin metal, it has to be round, it has to be perfectly flat (sorry, Robin,
no woks; flatness is required for equal cooking without stirring - no
stir-frying here), it has to have two handles (not one long one), it has to
be extremely shallow (2 inches). A classic one is about 16 inches in
diameter for six persons as a main dish or eight as an entrΘe.
To make things simpler, look at a real paella and at the main steps in
preparing the dish in a Valencia-based link I've located while web surfing:
(The recipe itself, by local chef Juan Carlos Galbis, is a bit debatable.
But the steps are correct. Please also note one of those gizmos which,
applied to a gas stove, allow for equal head distribution, always crucial.
Ideally, in Valencia, the paella valenciana is a country picnic dish that
you make on a fire of either orange tree branches or vines. As you all
know, the type of wood is crucial for such dishes, since the steam will
condense above it and the aromas and flavors will fall back into it. If you
use pine wood, you'll get an unpleasantly resiny paella.)
More notes. "Paella valenciana" is the mother of all paella dishes, and the
only one that, in Valencia, uses the recipient's name; the others are known
as "arroz con..." ("rice with..."): seafood, garbanzo beans, squid,
whatever.
Rice was planted by the Arab settlers in the Albufera swamps back in the
Middle Ages and has been the Valencia staple ever since. The farmers'
original version can be entirely vegetarian or include some chicken
(sometimes, locally, duck) and rabbit; if available, small mountain snails.
What it does NOT include is: crustaceans, fish, pork, lamb, bell peppers,
mountain ham, artichokes... (There are "arroz con..." versions for all of
that. But I'll stick to the basic recipe).
The rice to be used is all-important. Try and find medium-grained
Calasparra rice from Spain, which soaks up the juices and flavors while
keeping its shape and finishing "dry". Arborio rice, ideal for risotto, is
not advisable at all -- too soft and tender. Spanish rice is never washed.
"Hard", chalky water is preferable, curiously, to sweet mountain water; you
can add a teaspoon of sodium bicarbonate to "harden" such water.