Verjus (or verjuice) is made from the juice of unripe grapes or. It was the prime source of sourness in the Medieval kitchen, but fell off the culinary map when lemons and tomatoes started being imported. Recently though, verjus has experienced a revival — largely thanks to Australian vigneron Maggie Beer, who produces verjus and has written widely on the subject, as well as developing lots of recipes to showcase the product.

Verjus is not as sharp as vinegar, but is more tart than white wine, making it an interesting and versatile ingredient to cook with. Traditionally, verjus was a cheap artisanal product, and there are lots of guides on how to make your own online. Commercial verjus is tricky to track down in Britain, but is available in a few specialist shops. It's also possible to purchase bottles through online shops of numerous New World vineyards.

In a savoury context, it's best to think of cooking with verjus as with white wine. Use a splash to deglaze a pan after cooking, add to sauces, risotto and vinaigrettes. In a sweet context, it's best to think of cooking with verjus as with lemons — as they have similar acidity levels. If adding to a sorbet or curd, then make sure that you keep tasting, so that the sharpness is not too pronounced.

Verjus is a versatile ingredient which works with anything from a vinaigrette for green leaves to a marinade for chicken.

The clean, crisp flavours also go with more delicate dishes like Hulston's verjus and spring onion sauce which is served with halibut.

As verjus has a lemon-like acidity, it can also be substituted for citrus fruit in recipes. Seventeenth century French chef Pierre de la Lune used verjus for the filling of a pastry tart, not dissimilar to a Tarte au Citron.

Frances Atkins uses verjus as a piquant glaze for her sweet mango dessert, andPied a Terre uses verjus for the citric aspect of its cocktail Le Verger, mixing it with vodka, Calvados, sugar syrup and tonic.