KATHERINE MACALISTER tries a taste of Mexico the Speedy Gonzalez way in Oxford city centre 'Guacamole?" The Mission staff member asked an octogenarian next to me.

"I don't know, I've never tried it, but it sounds very exciting, " he said, watching the avocado mixture being added to his burrito filling.

On the other side of me, a student was already feasting on what has become one of Oxford's biggest success stories of the year.

Mexican food has arrived in Oxford and it's going all the way!

In November alone, owner Jan Rasmussen sold 10,250 burritos. There is certainly no credit crunch going on in this section of St Michael's Street. And, surprise, surprise, there are more Mission's in the offing, with another venue being planned in Oxford, and others around the UK.

"Yes, it's the perfect time to be expanding, really, because there are so many great premises on the market right now at reasonable prices, " Jan grinned.

That Jan has cornered a gap in the market is obvious. Oxford has been crying out for a decent South American restaurant since the demise of La Cantina and, although there are only 20 spaces at the trestle tables in The Mission, the food is literally racing out the door.

"When we are up and running, we can make a burrito every 30/40 seconds, " Jan added.

And nothing gets lost in the process. But then, with an obsession for Californian-Mexican cuisine, and having lived in The Mission district of San Francisco, it was an obvious venture for Jan when he moved back to Oxford from the States.

"It's such quick, filling, cheap and tasty food, and everyone likes it, " he said, his customers on a Tuesday lunchtime proving the point.

"So, when I came home, I knew there was a place for it here, " Jan added.

Trained as a management consultant, he quit his job, opened the premises in St Michael's Street last March with his wife Sharon, and has now delegated his managerial responsibilities, so he can concentrate on his expansion plans.

So what's the secret? Having tried one myself, I can say that in terms of sheer quantity alone, the burritos cannot be beaten.

Each weighs at least half a kilo, once you have stuffed it with a choice of pork, chicken, vegetable or steak, black beans, rice, cheese, sour cream, chilli sauce and guacamole.

Choose from burritos, fajitas, tacos or salad and a drink from the fridge, and Bob's your uncle - lunch or dinner when and how you want it.

Decide on what kind of chilli heat you can cope with, and then just stand back and admire the professionalism of the staff.

They warm the tortilla, add the ingredients and have it rolled, bound and served with a serviette in a steel basket before you can say enchilada.

But it is the details that count. The chicken, for example, is marinated in chipotle adobe (a kind of chilli) and roasted in a tinga sauce, and the carnitas is slow-roasted pork, seasoned with thyme, bay leaves and orange zest and cooked until it falls apart.

In terms of cost, the 37-year-old again comes out on top, because The Mission has a kitchen downstairs where his Mexican chef, Victor, makes everything fresh.

"If we run out of salsa we chop up some more tomatoes, " Jan said, "so there's no need for fried or frozen food."

So how quickly did he know The Mission would work?

"Well, we broke even within the first week, " Jan grinned. "And there has been a real buzz about it ever since."

But don't be fooled. Jan did his homework and even opened Green's Cafe on St Giles to give him the experience needed to run a small business. Only then did he attempt The Mission.

"Yes, this has been planned for three-and-a-half years, " he admitted.

As for the credit crunch statistics, Jan knew them already.

"I think it's magazines, restaurants and women's fashion shops that are the most likely businesses to fail, and in that order, " he grinned again.

"So yes, we knew we'd got it right from day one when we opened the doors. And we know people like it, because they have been trying to open franchises in China and Australia already, " he added.

"But then it's so much easier than a proper restaurant, because all we need is a counter and a small kitchen to make it work. What is important, however, is location."

So what next? We ll he is close to signing on the next Mission on Oxford's High Street, to capitalise on the Mission's popularity with students and tourists, and then he will go elsewhere with other university towns being at the top of the list - Bristol, Reading and Edinburgh already being discussed.

"But I am also looking forward to developing the brand and carving out an identity for The Mission, " he explained.

But the big question is, after all this, can Jan stand the sight of a buritto himself?

"I try to restrict myself to five a week, " he laughed.

There you go, he's putting his stomach where his mouth is. A surefire recipe for success. The burrito revolution has begun.