A Short Season Worth Waiting For

Every January, boxes of knobbly, deep-orange Seville oranges appear on greengrocers' stalls and market tables, and then vanish again by early March. They are far too sour and bitter to eat out of hand, which is exactly why they make such extraordinary marmalade. The bitterness of the peel, the generous layer of pith and the plentiful pips all contribute pectin, so a good Seville will set firmly with nothing more than sugar and patience. Buy them when you see them, and buy plenty — they freeze beautifully, whole, for up to a year.

If you grow citrus in a conservatory or a large pot, you may manage a few fruits of your own on a bitter orange tree, but ripening in a British winter is unreliable. Treat home-grown fruit as a bonus and rely on the Spanish crop for the bulk of your preserving.

Gathering Your Proportions and Kit

Marmalade is unforgiving of guesswork, so weigh everything. A reliable starting ratio is 1kg of fruit to 1.7 litres of water and 2kg of sugar.

• Fruit and sugar: 1.5kg Seville oranges, 3kg granulated sugar (never use preserving sugar with added pectin here — you don't need it).
• Water: about 2.5 litres, plus a little extra for topping up.
• Pan: a tall, wide, heavy-based preserving pan. Marmalade climbs the sides alarmingly as it boils, so leave plenty of headroom.
• Kit: a square of muslin and string, a jam thermometer, a couple of saucers chilled in the freezer, and seven or eight sterilised jars with wax discs and lids.

Wash the fruit well, scrubbing away any wax or grit, and discard any that are soft or mouldy.

Preparing the Peel

Cut each orange in half across the equator and squeeze the juice into your pan, saving the pips. Scoop the pith and pips out with a spoon and tie them loosely in the muslin — this bag is your pectin insurance and it will go into the pan with everything else.

Now shred the empty halves. A sharp knife and a steady hand give the best texture: anything from a chunky 5mm strip to a fine 2mm shred is legitimate, though thick-cut marmalade takes longer to soften. Work through the pile in batches and don't rush it, and don't be tempted to blitz the peel in a food processor, which bruises it and leaves you with cloudy, uneven shreds.

The Long, Gentle Simmer

Add the shredded peel, juice, muslin bag and water to the pan. Bring it slowly to the boil, then reduce to a steady simmer, uncovered, for around one and a half to two hours. The peel is ready when a shred crushes easily between finger and thumb against the side of the pan, with no chalky resistance left in the middle.

Lift out the muslin bag and let it cool enough to handle, then squeeze it hard over the pan — this releases the pectin-rich liquid. Top the pan up with hot water so the fruit and liquid together come to roughly the level you started with; you want plenty of liquid for a clean, bright set.

Sugar, Boiling and the Setting Point

Warm the sugar in a low oven, then tip it in and stir over a gentle heat until every grain has dissolved. Rub a little of the liquid between your fingers — it should feel smooth, never gritty. Only then turn up the heat and bring it to a rolling boil.

Boil hard for 15 to 25 minutes. Stir occasionally to stop it catching, and skim off the grey foam that rises with a slotted spoon. A jam thermometer should read 104–105°C, and a knob of butter stirred in at the end helps disperse the last of the scum.

Testing, Potting and Troubleshooting

Take the pan off the heat and drop a teaspoon of marmalade onto a chilled saucer. Leave it a minute, push it with your finger: if the surface wrinkles and the blob holds its shape, you have a set. If it stays liquid, boil for another five minutes and test again on a fresh saucer.

Let the pan settle for ten minutes, then stir once to distribute the peel before ladling into warm sterilised jars. Fill to within a few millimetres of the rim, cover with a wax disc, and seal while hot. The marmalade will keep for eighteen months or more in a cool, dark cupboard.

• Runny set: return to the pan with 100g extra sugar and the juice of a lemon, dissolve, and boil hard again.
• Too stiff: add a splash of hot water, reboil briefly, and retest.
• Tough peel: simply undercooked — next time simmer longer before the sugar goes in.
• Dark colour: sugar caught on the base, or the boil was too fast once sugar was added.

For a softer, darker, old-fashioned Oxford-style marmalade, simmer the whole oranges for two hours first, then shred the softened peel and finish as above. Either way, a spoonful on hot toast in July is one of the best arguments for a cold January morning's work.