Chef Ferran Adrià is not some tempestuous Gordon Ramsay, or certainly he appears not to be one, in this brilliant documentary film from 2010, which opens at the Lighthouse tomorrow, Friday 27. Considered by many to be the most innovative chef in the world, Adrià would be too serious about food to agree to participate in a spurious kitchen TV exercise, I'd imagine. So, whatever this is, it's not that.

Nevertheless, quite early on in the homage, you do sense the stainless steel that rules the kitchen of El Bulli. "Don't give me anything bad," Ferran says, backing away from Oriol Castro, one of his two Chefs de Cuisine, who has just offered him some displeasing delicacy. The next shot shows him being spooned more sample stuff like a little boy. Ferran simply puts on that "must try harder" look again and moves away once again from his second-in-command.

Indeed, "must try harder" is very much the governing principle of the first half of this film. We first meet Ferran and his aides as they prepare to decamp from the world-famous El Bulli restaurant, which is situated by the tranquil cove of Cala Montjoi on the Costa Brava. Or was situated, in fact, as El Bulli is now a foundation. No longer a working restaurant, it is not taking any bookings. This development could usefully be the matter of another fascinating documentary.

But in the film, it’s October 2009, the summer season is over, and Ferran is pointing to a flip-chart, as he issues instructions in a clipped, guttural Catalan. He tells his two head chefs what cooking equipment must be transported into El Bulli Taller, the restaurant's food 'lab' in Barcelona.

For this is where they will be holed up for six months. Not far from their billet on the Carrer Portaferrissa will be the vast Boqueria food market, from where Ferran and his dedicated chefs will source the ingredients for the yet-to-be-dreamt-up dishes that will grace his tables for the 2010 summer season, back on the Costa Brava.

Ferran is co-owner of El Bulli with Juli Soler, typically employing at that point a staff of between 60 and 70, including 35 cooks - more staff than diners. The restaurant was getting two million reservation requests each year, but only 8,000 got to dine there, 50 each evening, 160 days per season. Diners didn't choose from a menu. Each guest was served between 28 and 35 small portions, including cocktails, snacks, tapas and desserts. Needless to say, the restaurant and its driven chef/co-owner have a staggering array of awards, quite aside from the three Michelin stars. Space hardly permits, in fact.

In the film, we see some interesting exchanges at the Boqueria market, which, as many Irish visitors will know, is situated just off the Ramblas. It’s a ‘lab’, not a kitchen, mind, so you see Oriol Castro requesting five big grapes, and asking for a receipt - he laughs, yes, but he still wants a receipt. Correspondingly, in a later scene, we see El Bulli's second Chef de Cuisine Eduard Xatruch carefully uncrumpling a bunch of receipts and straightening them out into a neat pile.

This is Catalan thrift, but Catalan thrift always makes sense. An efficient lab isn’t one you return to with a big bunch of grapes which might end up going mouldy on the work-top. So there is a fascinating laboratorial logic about a small purchase such as the five grapes.

And back at the lab, they do things with food that are kind of mind-blowing. They casually mention chemicals you have never heard of, they do things with nitrogen, and they seal their little packets of ravioli with an edible cling film, made from - oh I can’t remember what. Oh, and the pasta dissolves the instant it is dipped in water.

In another scene, it’s winter now, and Ferran and one of his head chefs are buttoned up in their jackets against the ultramuntanya, the wind from the Pyrenees, blowing through the Boqueria market. They meet Mollusc Man – we don’t learn his name - who stands by an iced stall on which a great, cautious langoustine slowly moves. Mollusc Man won’t tell Ferran about what will be in season in coming months. That, he says, would be giving away trade secrets. “How might that be giving away a secret?” Ferrran counters, frustrated with the man’s preciousness. Surely there must be a calendar somewhere with molluscs matched to their seasonal availability. He would like to get his hands on one.

Born creators – 'innovators' is much too mild a term - Adrià (born 1962), Castro (born 1974) and Xatruch (born 1981) were in 2009 still doing this utterly brave thing every year. They threw away the menu and found a new one, setting a painful challenge both to themselves and to their staff. Ferran has a kind of reluctant steely demeanour, but he is essentially a modest, shy man who doesn't do much in the way of hissy fits. The challenge, as he explained to his workforce wouldn't be over just because they would finally get a new menu. It would have to be tested at the tables, during those first nervous weeks after El Bulli's June 16 opening.

The film is brilliant, honest and I suppose kind of raw (it's impossible to avoid the culinary euphemisms.) As you watch, you begin to think - and surely the German production team intend you to think this - that Ferran is a kind of a driven Miró or a possessed Picasso. His endlessly mobile eyes ruminate and move away from whatever situation he is in. He is thinking distractedly all the time, trying to find a way out of the flux and chaos of the creative maelstrom. He seems to suffer a bit for his art; the wild impulse of experimentation doesn’t make him visibly happy. However, as the film draws to a close, and the June 16 opening beckons, you see a man getting more gung-ho and sanguine. He smiles much more, and his autumn/winter gruffness dissipates.

In fact, Ferran looks like a guy who couldn’t give a hoot about acquiring wheelbarrow loads of money - thrift is a different matter - so correspondingly one only briefly wonders what kind of money those diners are paying. We watch a few of the waiting guests sheepishly gather outside the windows of El Bulli as the restaurant prepares to open once again. The customers are always brought through the kitchens before they sit. Under no circumstances can anyone be seated without a reservation, it would set a precedent that Ferran doesn’t want.

The restaurateur is an amazing creation himself, not to speak of his food. We learn absolutely nothing about his domestic life, but because the camera is so focused on his reactions in the matter of food, we seem to learn an awful lot about him personally. Married, kids, divorced? Ni idea, as they say in Spanish. What does he like to do on his time off? Not a rasher's. It seems he was raised in L'Hospitalet de Llobregat, a none-too-pretty working class district to the west of Barcelona.

Sure, he is undoubtedly like this all the time - sceptical, hard-nosed, default unimpressed, simmering, teasingly demanding. But it’s as though the cameras, by focusing relentlessly on him, have somehow piped him through the lens - just like one of the frothy confections that have made him famous the world over, in fact. It's as though the German makers of this film – an efficient, no-nonsense lot themselves - have extruded him from the rest of the characters, and made him what he is.

That may sound like a long-winded way of saying that this is just another slice of kitchen Reality TV then. But somehow there is a distinction - he is so there, so present all the time even when he is off camera that you feel the camera has built him for us, or pitilessly extracted essence-of- Ferran for our hungry eyes.

And if you were in the restaurant business, you might be fascinated to learn how he does things. Absolutely nothing is coyly hidden. Much is discussed on the hoof, much remarked upon as Adrià, Castro and Xatruch let things rest upon their palates to savour and cold-bloodedly react and analyse. You see how they do things; you see them suggest more of this and a little less of that.

Mid-way through the film, Oriol Castro goes a deathly pale when the hard drive on the lab computer goes. The fact that the details of every lab experiment this winter has been printed out and filed in binders, that photographs have been taken, that meticulous documentation has taken place is simply not enough. Ferran wants things stored on computer. He doesn’t want any more of these reams of paper. He wants a paperless lab, as it were. It’s a bit obsessive the way he goes on about this, and it is the only time you see him genuinely angry.

But the truth of it is that his aides in culinary design are so confident of their art that they let him fume on. He knows this too, and the small storm quickly passes - such are the mores of the place. However, that confidence, no matter how much you have of it, doesn’t carry you much beyond the immediate situation.

There is an absolutely riveting scene towards the close where the chefs are serving Ferran the new menu, dish after dish, a seemingly endless array presented for his approval. There he is, seated at table as though he were the paying guest, tasting, commenting, ruminating. At one point, they serve him a plate of something and the expression on their faces is something to behold – they are almost willing him to like the glorified morsel. Yet he pauses and pauses for what seems like an excruciating 15 seconds or so before he finally gives the nod.

But if he had happened to express disappointment, we know Ferran well enough at this point to discern that he would be disappointed principally with himself. He wouldn’t criticise his chefs at this late stage; it would be disingenuous and unfair. He is the classic mucker-in, and the buck stops with him - the opening evening looms very close.

And just to show that Ferran Adrià knows this food design business is, in the end, all a bit arbitrary anyway, there is a telling scene towards the close. Oriol Castro enters the kitchen having served a table of guests with a cocktail to which he has added carbonated water, rather than the required still water. “I turned pale when I saw the bubbles forming,” he tells his boss.

Anyway, what the hell, Ferran and his Chefs de Cuisine mix the carbonated water and the oil themselves, to see what it might be like. Ferran duly tastes it, putting on that me-I’m-only-in-it-for-the-craic face again. He wryly smiles, and concludes that the delicate cocktail works anyway with carbonated. This revealing scene is presumably there to illustrate the trial-and-error principle that ruled El Bulli, season after season. But it would be grossly unfair to write Ferran off as smoke and mirrors; it wasn't that kind of restaurant.

Paddy Kehoe