When temperatures fluctuate, the nation’s diet switches overnight from salads to stews and casseroles, but hope still springs eternal on the retailers’ shelves.

Tesco’s range of Lasting Leaf has let the cat out of the bag on its extended freshness on the pack information. It’s a nutritionist called Sandrine, who discovered crispness could be enhanced by two days simply by first dipping the leaves in warm water and then putting them through a cold drench “for just the right amount of time” - an experiment which took 10 years to perfect.

The new range includes frisée, lamb’s lettuce and radicchio at £1.30/250g and iceberg, romaine, red cabbage and carrot at £1.30 for the same weight.

And there’s nothing like making a good idea easier to boost the convenience range. Sainsbury’s has a fajita mix at £1.50/380g, which comprises shredded red and white onions and peppers.

Soft fruit is still on the shelf in abundance, although Morrisons has come up with something different from the traditional punnet with a lid. For £3.25, there’s a 600g Spanish mini tray of the Huelva-based Guaperal supplied Candonga variety. The tray is made out of hardboard with the traditional ‘pegs’ at the corners.

It has also further defined its range of aubergines, identifying the round variety from Italy as Sicilian at £1.99 each, and the mottled long type from the Netherlands as Graffiti at £1.99 and £1, respectively. Also in store are rambutans from Vietnam - mainly known for its export of dragonfruit - at £1.40/100g.

Nearer home there is another newcomer on the block in Marks & Spencer’s organic tomato section. Grown in Portugal and priced at £1.99 for 180g, the contents of a kraft tray is the vine-ripened Tomalini variety. -