Jam season is here - bottle that sunshine now to brighten up the winter

The ideal time to make lemonade, when lemons are juicy and plentiful and cheap, is in the dead of winter, when the last thing you want is a cooling glass of lemonade. Similarly, jam-making is best done on a grey November afternoon, when the windows are steamed up and the kitchen is the warmest place in the house. Winter is exactly when you want to be standing over a great pot of bubbling fruit and boiling sugar, but much less so in summer, which is when all the good fruit is in season. From May until mid-October, our fruit supplier bills spike exponentially as boxes and boxes of seasonal fruit in its absolute prime make their way to our kitchen for a jam session, and the practice of turning them into a sweet spread is part profession, part obsession. Jam is very much our jam.

Early in the season, we can just about cope. The soft fruits start to come in when the weather is still behaving itself, and we love giving them a little seasonal accent – elderflower comes with the last rhubarb, as well as with the first strawberries and apricots, and it pairs wonderfully with all of them (if you are starting there, Felicity Cloake has a very thorough guide to the perfect strawberry jam). Cherries, meanwhile, go with just about anything, while young bay leaves often find themselves heading into the blackcurrant pot. Fennel fronds and peaches are another favourite, and we make some whenever we can get those two at the same moment. It is an amazing combination: sweet, perfumed and just a little bit green.

Intriguing … Lillie O’Brien’s fig and earl grey jam. Photograph: Linda Nylind/The Guardian

For us, the real preserving frenzy begins round about now, at the deep, sticky end of summer. In fact, September may well be the best jam month of all. The days are not too hot and the produce – figs, plums, grapes – are the ultimate jammers. Plums offer near endless possibilities and, depending on the variety, can take a surprising amount of spice: cassia bark, star anise, perhaps a clove or two. Nigel Slater’s collection of late-summer jams and pickles is exactly the sort of thing to read when the fruit bowl begins to look threatening.

Grapes, meanwhile, are a bit of a challenge, not least because most of the varieties grown commercially are chosen for their sweetness, whereas you want something else for jam: there needs to be some acidity, some funk, some flavour in there. Fragola grapes, with their musky, intoxicating, wild strawberry flavour, are a rare treat – we usually get only one delivery of them each year, which makes them all the more special, and all the more worthy of preserving for the rest of the year.

Figs, especially those beautiful, black bursa ones, make the best jam of all, and the one that we and our customers crave the most. The fruit hardly needs any help, either, although its honeyed sweetness loves nothing more then a few pods of cooling cardamom for balance (that said, we are more than a little intrigued by Lillie O’Brien’s earl grey combo).

Our annual September challenge, then, is simple: make enough fig jam to last until Christmas. Every year, we make what looks like an absurd quantity. And every year it disappears far too quickly, which is exactly the point – spend a bit of the summer sweating over the pots so that in winter, when we aren’t sweating at all, there’s a little bit of jarred sunshine ready for us when it is most desperately needed.

Our month in food

Happy new year … Claudia Roden’s honey cake. Photograph: Romas Foord/The Observer

The sweet spot | Jams aside, our pastry kitchen currently smells heavily of honey and spice as we get busy baking loaves and loaves of honey cake in readiness for the Jewish new year next week, which this year is coming round earlier than usual. It is traditional to start the year with something sweet, be that an apple dipped in honey, dates, sweet challah bread and, of course, honey cake. You don’t need to be Jewish to enjoy this delicious tradition: on the 11th, wish your Jewish friends a happy new year, and have something sweet for yourself.

Local attraction | Our love for Jackson Boxer’s cooking knows no bounds, and even though his Brunswick House is so close to our home in south London that we are there more often that is OK to admit, whenever he opens a new place, we go. Vesper is on Exmouth Market in the centre of London, and it made us question our loyalty not only to Brunswick House, but also to our own home and our beloved neighbourhood, because the fried potato pizzette is something we need to live closer to.

Book marks | We got a sneak preview of two new books that are already making our autumn look much more delicious, and both of which are published today. Simple Too by Yotam Ottolenghi is full of mouthwatering recipes that look and taste as good as they are easy to make, and promises to add a touch of glamour to our midweek meals. The second is the new one by Fuchsia Dunlop, a perennial favourite of ours, and Five Tastes: The Magic of Flavour in a Chinese Kitchen is a deep and delicious dive into the flavours that are the cornerstones of Chinese cooking. We are into all of them.