How to pick fruit and sabzi that last the week.

The three tests that work on almost anything

Weight is the best single indicator on the shelf. Produce is mostly water, and everything that goes wrong after harvest starts with water leaving. Two shimla mirch the same size will not weigh the same, and the heavier one is the fresher one. This works on nimbu, kheera, baingan, gobhi and every citrus fruit.

The stem end is the second test. A vegetable is cut from a living plant, and the cut is an open wound: it dries, browns and lets moisture escape. A pale, damp stem scar means recent harvest. A brown, sunken, dry one means days on a shelf, whatever the body still looks like. On tamatar, shimla mirch, baingan and karela the little green calyx around the stem browns and curls first, well before the skin gives anything away.

The third test is how you press. Use the flat pad of your thumb, press slowly, and feel for a springy give that comes back. A fingertip jabbed into an aam or a tamatar bruises it, and that bruise is where the rot begins two days later.

Fruiting vegetables: tamatar, baingan, shimla mirch, kheera

A good tamatar is heavy, taut and slightly glossy, and it gives just barely at the shoulder when you press. The stem scar should smell green and tomato-ish when you hold it to your nose; if it smells of nothing, it was picked hard and gassed, and it will taste of nothing. Avoid soft shoulders, split skin around the crown, and the pale hard core you can sometimes feel through the top.

Baingan should feel light for its size, which sounds backwards after everything above, but a heavy aubergine is a seedy one. Press it and the skin should spring straight back; a dent that stays means the flesh inside has already gone spongy. The green cap must look alive, not dried and brown at the edges.

Shimla mirch wants thick, straight shoulders and taut skin, and it softens first right around the stem, so squeeze there. Kheera should be firm along its whole length, ends included, because that is where it goes first; one that bends is finished. Karela should be deep green with sharp ridges, since yellowing means the seeds inside have hardened.

Pods: bhindi, matar and phalliyan

Pods are the easiest category in the shop, because there is a physical test. Bend the tip of a bhindi. If it snaps cleanly with a crisp break it is young and tender; if it bends without snapping it has gone fibrous and no amount of cooking will fix that. Keep to small and medium pods, roughly the length of a finger, and pass on anything with hard ridges or dark blotches.

Matar pods should be plump but not straining. A pod stretched drum-tight is over-mature and the peas inside will be starchy rather than sweet. A light, flat, wrinkled pod has lost its water. The pod should feel slightly velvety and should squeak faintly against itself. If the shop lets you, open one and eat a pea — nothing else tells you as much.

Roots and bulbs: aloo, pyaz, gajar, muli, adrak, lehsan

These keep the longest of anything you buy, so it is worth being fussy. Aloo should be rock firm with tight skin and no give at all; wrinkles mean it has been out of storage a long time, and sprouting eyes mean it is on its way to becoming a plant. Green patches under the skin taste bitter, so pare them away generously or leave that potato behind.

Pyaz is judged at the neck. It should be dry, tight and papery, with no green shoot pushing through and no dampness. Squeeze the base: any softness there and the onion is rotting from the root plate upwards. Lehsan should feel solid as a stone, with cloves you cannot move against each other under the skin.

Gajar and muli are sold two ways, and the version with leaves still attached tells you far more — perky leaves mean it was pulled recently, and limp yellowing ones mean it was not. Both should snap rather than bend. Choose small to medium muli: the big ones turn pithy and hollow in the middle and fiercely hot. For adrak, snap a knob off. It should break with a crisp fracture and a strong smell, and the skin should scrape away under a thumbnail. Thick, tough skin that resists means an old, fibrous root.

Leaves and brassicas: palak, methi, dhania, gobhi

With leaves, look at the bottom of the bunch, not the top. The stalks near the tie are where yellowing and sliminess begin, and a bunch can look green from above while its base has already turned. Snap a stalk: palak and methi stalks should break with a wet crack. Hara dhania is the shortest-lived thing in the shop because its leaves are thin and have almost no waxy coating, so it loses water faster than anything else — buy it with roots on if you can, and buy it last.

Gobhi is a density question. A good head is heavy for its size with a curd so tight you cannot see between the florets, and the jacket leaves should be green and clinging rather than trimmed off. Black speckling on the curd is mould starting, and it spreads inwards.

Buying for a week instead of for tonight

The mistake is buying everything at the same stage of ripeness and then racing it. Stagger it deliberately. Buy some bananas yellow and some still green at the tips so Thursday has fruit too. Buy two tamatar soft enough for tonight's salan and the rest firm. Put the leaves and the delicate fruit into the basket last and unpack them first.

Order matters on the way home as well. A bag of aloo sitting on top of a bunch of dhania crushes it into a hot green paste in twenty minutes, and bruised produce spoils from the bruise outwards. Heavy at the bottom, leaves on top, and out of a parked car as soon as you can manage.

• Buy fruit at two stages of ripeness so the week is covered.
• Skip anything pre-cut or pre-trimmed. A cut surface is an open door.
• Unpack the bag rather than storing it as it came — one bad item spoils its neighbours.