There is a particular pleasure in arriving at a Saturday market with no list, a canvas bag and an hour to spare. Instead of deciding in advance what you will eat, you let the stalls decide for you. A tray of just-dug new potatoes, a bunch of cavolo nero with frost still on it, a punnet of rhubarb the colour of stained glass. Shop like this and the week's cooking almost writes itself.

Buy what looks best, then plan backwards

The trick is to shop in two passes. Walk the whole market once without buying anything, noting what is genuinely good rather than merely available. On the second lap, buy generously from the two or three stalls that impressed you most.

Then, on the way home, plan loosely. Not a rigid menu, but a set of intentions: something with the greens on Monday, the roots roasted midweek, the soft fruit eaten raw before it turns. A loose plan bends when your week does. A strict one breaks.

• Buy the backbone generously: onions, carrots, leeks, potatoes and a good cabbage will carry several meals.
• Buy the treats modestly: a small piece of excellent cheese beats a large piece of dull cheese.
• Buy one thing you have never cooked — kohlrabi, salsify, a bunch of wild garlic in spring.

The pantry that makes market cooking work

Market produce is only half the story. The other half is the shelf behind you at home. Keep these basics stocked and almost any basket of vegetables can become dinner.

• Fats: olive oil, a neutral oil, butter, and a tin of good dripping or lard.
• Acids: lemons, vinegar, capers, a jar of cornichons.
• Salty and savoury: anchovies, olives, stock cubes, soy sauce, mustard, tomato purée.
• Storecupboard bulk: rice, dried pasta, lentils, tinned beans, barley.
• Flavour bombs: garlic, ginger, dried chillies, cumin, fennel seed, a jar of harissa.

With these in place, a bag of chard and a few potatoes is not a side dish waiting for a main course. It is supper.

Breakfasts that flex with the basket

Breakfast is where loose planning pays off fastest. If you have eggs, bread and one vegetable, you have a dozen breakfasts.

• Greens on toast: wilt spinach, kale or spring greens in butter with a pinch of nutmeg, pile onto toast, top with a poached egg.
• Market mushrooms: fry hard in a dry pan first, then add butter, thyme and a splash of sherry vinegar.
• Seasonal fruit: rhubarb stewed with orange zest in spring; sliced plums and yoghurt in late summer; stewed apples and oats from October onwards.
• Tomato on toast, properly: grated ripe tomato, olive oil, salt, on bread rubbed with garlic. Only worth making in August.

Cook a little more than you need. Cold frittata and leftover stewed fruit make the next morning easier.

Lunches built from odds and ends

The British market lunch is a bowl of whatever is left, improved with a dressing and something crunchy. Think of it as a template rather than a recipe.

• Base: grains, lentils or yesterday's potatoes, roughly chopped and fried until crisp.
• Bulk: roasted roots, blanched beans, shredded raw cabbage or grated carrot.
• Something salty: a crumbling of cheese, a few anchovies, olives, or a spoon of pickle.
• Dressing: three parts oil, one part vinegar, a teaspoon of mustard, salt and pepper.

If you have soup stock from Sunday's chicken or a pot of beans cooked on Monday, lunches for the rest of the week are five minutes' work. A jar of cooked beans in the fridge, kept in their liquor, is one of the most useful things you can have on hand.

Dinners that follow the produce

Midweek dinners should be forgiving. Build them around one vegetable at its peak and let that vegetable lead.

• One-pan roasts: sausages, wedges of squash or potato, halved onions and a few bay leaves, all in a hot oven for forty minutes.
• Braises: leeks, celery and carrots softened in butter, then lentils or barley and stock. Finish with a spoon of mustard.
• Fast pasta: purple sprouting broccoli or courgettes cooked hard in oil with garlic and chilli, tossed with pasta and a little of the cooking water.
• Fish on a Friday: whatever the fishmonger has that is bright-eyed and firm, roasted with fennel and lemon.

If you grow even a little — a windowsill of herbs, a pot of chard, a couple of tomato plants — the market basket and the garden start to feed each other. A handful of your own parsley turns a plain bowl of beans into something worth eating twice.

End the week with a clean-out supper

By Friday, the basket is down to odds and ends. This is not a problem; it is the best meal of the week. Fry whatever is left — the last of the greens, a bendy carrot, half an onion, a stub of cheese — in a wide pan, add stock and a handful of rice or pasta, and let it simmer into a thick, comforting soup. Finish with a squeeze of lemon and a drizzle of oil.

Shop this way for a few weeks and you will stop thinking of the market as a treat and start treating it as your larder. The produce tells you what to cook, your pantry fills the gaps, and the week's meals come together with far less effort than a rigid plan ever requires.