Limp, shop-bought sandwiches are out. Exotic, home-made salads are in. Sales of lunch boxes are soaring as workers pack their own. By Rachel Shields

Such had been the extent of its decline that the term "lunch box" had come to be associated more with a certain 100m sprinter than with carrying midday meals. But as food prices remain sky high and disposable income shrinks fast, the packed lunch is enjoying an unlikely renaissance.

And with it no longer the preserve of school playgrounds, the content of the nation's lunch boxes is changing dramatically. Out go limp cheese and ham sandwiches on white bread; in come exotic fruits, mixed salads and experimental pasta dishes.

Yes, the next phase of the foodie revolution is all about mobility and making it yourself. Sales of food and drink containers are rising. At the same time, this shift in the way we eat – dubbed the "credit munch" – is hitting the takings of sandwich makers and fast-food restaurants.

Thermos, whose food and drink flasks are often viewed as the preserve of hikers and the elderly, has seen a 30 per cent increase in sales over the past year. And at the retailer Robert Dyas, sales of lunch boxes have risen by 68 per cent, year on year.

Inspired by cookery programmes and the lunch recipes created by celebrity chefs – from Mark Hix's Cornish pasties to Jamie Oliver's pasta salad – the nation is looking beyond swift snacks and bags of crisps.

"People are definitely making more exotic lunches now. Puy lentils, feta cheese, couscous, haloumi... they are taking their cue from the high street. They see things like oriental salads at places like M&S, and think 'I can make that'," said Janine Ratcliffe, food editor of Olive magazine.

Unsurprisingly, health campaigners, who have attacked some high-street retailers for selling sandwiches that are high in fat and salt, are celebrating this shift away from shop-bought lunches.

Lisa Miles, senior nutrition scientist at the British Nutrition Foundation, said that the surging number of people making food and taking it to work with them were more likely to be eating a better diet.

"You will be thinking about lunch in advance and preparing it at home, instead of grabbing something that you walk past in a rush, which might be unhealthy," she explained. However, Ms Miles added that people should resist the temptation merely to slap a slice of cold meat between two bits of bread. "Sandwiches are a classic, but it is important to vary things so that you get a range of nutrients and don't get bored."

High-street retailers around the country are feeling the effects of this newfound confidence. With profits plummeting, chains such as Pret a Manger and M&S are offering new "economy" choices and freebies in an attempt to hold on to customers.

Marks & Spencer's award-winning sandwiches and salads have long been popular with millions of British workers, but last week it announced that it is to slash food prices, following a 5 per cent drop in sales.

Meanwhile, the convenience-food maker Uniq, which supplies foods and ready meals to supermarkets across Europe, warned earlier this month that it expected to make a loss in the second half of this year, noting that sales of sandwiches had slowed significantly.

And at the end of last month the sandwich and salad chain Pret A Manger introduced an economy range, which includes a chicken, salad and rocket sandwich for £2.40. "We have launched a range of products that are less premium, to reflect our sensitivity to people's pockets," explained Simon Hargraves, the chain's director of food.

"People are still getting coffee, but not as much food as they used to," he added.

But statistics indicate that a growing number of cash-strapped commuters are also ditching their shop-bought coffee. On average a takeaway cappuccino or latte will cost £2.05, and many people have opted to brew their own at home and take it with them. Sales of Thermos portable tea and coffee mugs have increased by 40 per cent over the past year.

This shift away from ready-made lunches could also have a beneficial effect on the amount of food wasted. A survey commissioned by the Government's Waste & Resources Action Programme (Wrap), as part of its Love Food Hate Waste campaign, revealed last week that British workers shell out £5.5bn on shop-bought lunches each year, while leaving the same amount of food to go off at home.

Research suggests that if people make their own food they are less likely to simply chuck it out. Good ingredients, it is claimed, tend to hold their appeal for more than a single meal.

The classic British lunchtime recipe Independent chef Mark Hix's pasty

"The ideal packed lunch for me is a good old Cornish pasty. Traditionally they would sometimes be savoury at one end and sweet at the other, so beef, swede, potatoes, etc and maybe an apple pie filling the other end. Pasties also stay hot for a while, which means you don't have to deal with cold, lardy pastry. Here is a savoury version." Makes six.

For the filling:

200g swede, peeled and cut into rough 1cm pieces; 1 large baking potato, peeled and cut into rough 1cm pieces; salt and freshly ground black pepper; 2 tablespoons vegetable oil; 2 onions, finely chopped; 500g rump or rib steak, trimmed of fat and chopped into 5mm pieces; 250ml beef stock (or a good-quality beef stock cube dissolved in that amount of hot water); 1 tablespoon Worcestershire sauce.

For the pastry:

500g plain flour; 2 teaspoons salt; 125g butter, chilled and cut into small pieces; 125g lard, chilled and cut into small pieces; a little milk, to mix; 1 egg, beaten, to seal and glaze.

To make the filling: heat half the oil in a large heavy frying pan and gently cook the onions for 2-3 minutes until soft. Remove from the pan and put to one side. Heat the pan again over a high heat, add the rest of the oil, season and add the meat. Cook over a high heat for 3-4 minutes, turning until evenly browned. Remove the meat from the pan and add to the onions.

Add the stock to the pan together with the Worcestershire sauce, and boil rapidly until you have only 2-3 tablespoons of liquid left. Then add the meat and onions back to the pan and simmer until the sauce has reduced and it is just coating the meat.

While the sauce is reducing, cook the potatoes and swede in separate pans of boiling salted water until just tender, then drain and mix into the beef.

To make the pastry: mix the flour and salt together, then rub the butter and lard into the flour with your fingers, or mix it in a food processor, until it has the texture of fine breadcrumbs. Mix in some milk, a tablespoon or two at a time, until a smooth, rollable dough forms that leaves the sides of the bowl clean.

Roll out the pastry on a lightly floured board to a thickness of about 3mm and, using a plate or bowl as a template, cut out six circles about 18cm in diameter. Spoon the filling evenly on the centre of the discs of pastry. Brush around the edges with the beaten egg, and bring the edges of the pastry up around the filling. Crimp the edges together with your fingers, or roll the edges back over and then crimp them. Brush the tops with the remaining egg mixture, and cut a small slit in the top for steam to escape. Chill for about 30 minutes.

Preheat the oven to 200C/gas 6. Bake the pasties for 20 minutes, then turn the oven down to 180C/ gas 4 and cook them for another 20 minutes or so until golden.

If the pasties are browning too quickly, cover them with foil or greaseproof paper (if they are going to be reheated, finish cooking them while they are still quite pale brown).