An apple, a yogurt, a chocolate bar and a sandwich- that has been my lunch every day since I switched from mother's milk to solid food.

Ten months ago, I moved to Beijing. It took me just a day or two to recover from the jetlag - in all but one sense. Every lunchtime left me feeling thoroughly scrambled.

It wasn't that I didn't love the mountains of sticky gongbao jiding, the silky tofu in its clear broth or the fish heads gazing balefully up at me from their bed of chilies. But, somehow, the midday noodles and rice were throwing my body clock off kilter. I couldn't shake off that central part of my daily routine. Where was I to get a sandwich in Beijing?

At first, I resorted to a certain multinational sandwich chain. With every bite of stodgy bread, soggy salad and plastic cheese, I felt a sense of disappointment in myself. I had come to China to experience things, and here I was eating Subway.

After a few weeks that disappointment, coupled with several dozen Meatball Marinaras and Veggie Delites, began to weigh too heavily on my mind and my stomach. I became determined to go local and have lunch. My quest for a Chinese sandwich began.

The first problem was bread. In Britain and Europe, bread is crunchy on the outside, soft inside, salty and (if it's the pretentious artisan stuff upon which every North London resident thrives) studded with all kinds of fibrous, anti-heart-attack grains.

In China, bread is rarely any of these things. The first sliced loaf I bought in the bakery was so sweet that I had to save it until 4 pm and have it with a cuppa as my afternoon tea and cake.

There were more traditional Chinese dough-based offerings, but they, too, ended up falling at some hurdle along the way.

Mantou had the right salty flavor, and the yeasty hum steaming from each one as it was pulled from its metal vat was certainly promising. But the texture was all stodge and no crunch. I briefly experimented with baozi, telling myself that "dough outside, something inside" might be sandwichy enough. But, as with mantou, I couldn't get used to the dampness that lingered with every bite.

I tried thinking a little outside the sandwich box. Jianbing pancakes are ubiquitous in Beijing. With a little imagination, I tried to tell myself, a jianbing could almost be a wrap. I licked chili and unidentified reddish-brown sauce off my fingers and thought, mournfully, "What a tasty, eggy pancake." A pancake isn't bread. It isn't a wrap. It isn't a sandwich.

I tried a xianbing - but was put off by my iPhone dictionary's translation of it as "leek pie".

I tried a roujiamo - I liked the name because it sounded like the James Bond actor "Roger Moore" - but it was more like a burger and too heavy for lunch. Summer is definitely on its way, and I'd like to at least be able to contemplate fitting into my bikini.

Then, one day, I noticed a small, unremarkable restaurant near my house. A man walked out holding a folded piece of bread stuffed with meat and vegetables. Could it be ?

I raced in and grabbed a menu. Near the back I found the picture and an English description: "Donkey meat sandwich".

I hesitated. I'm a great Winnie the Pooh fan and, however miserable Eeyore was, Christopher Robin and his chums would never have resorted to skewering him on a kebab and sticking bits of him into a pitta, without spring onion. But I was too close to resolving my sandwich search to faff about with such sentimentalities. I took a deep breath. "Zhege (this one)," I told the server.

One bite and I knew I had found it. The right crunch, the right softness, juicy meat, not too heavy - the perfect Chinese sandwich. It was as if the delicate sauce and oozing donkey fat were oiling the cogs of my body clock back into action.

The trouble is, the donkey sandwich has become part of my routine. What am I going to do when I'm back in the UK and the clock strikes "donkey sandwich lunchtime"?