I spent a week in Paris from 11/18/06 - 11/25/06 in Paris and highly recommend dining at El Fogon. This was the best dining experience that I had in Paris--and I ate out every night, including at places like La Truffiere, etc. Note that contrary to current guides (e.g., 2006 Fodors) and internet info (e.g., Patricia Wells, etc.) El Fogon is no longer at the following address: 10, rue Saint-Julien-le-Pauvre. It moved approximately 1 year ago to 45, quay of Large Augustins/75006 Paris.
You must order the tapas (40 euros per person)--10 small selections decided by the chef for the evening. It was mind-blowing, a perfect mix of Spanish/Basque and French style cuisine. The tapas will be enough to satisfy a hungry person's appetite. If you have several people, some might order the paella, but I only ordered the tapas and so can only speak on their behalf.
Last, reservations are a MUST. If you don't have reservations, then you won't get sat or will be stuck at the bar--an impersonal space with 2 chairs in the back of the restaraunt.
Let me know what you thought.