Orange and Rhubarb Preserve

Ingredients

• 8 oranges
• 5 lb rhubarb, skinned and cut into pieces
• 4 lb sugar

Method

Cut the orange peel into quarters and blanch in water for five minutes to soften it, then drain. Slice the blanched peel into fine strips — this removes the bitterness that raw pith would introduce. Peel away the white pith from the orange flesh itself, then segment the fruit and remove all seeds and tough membrane. The rhubarb should be trimmed and cut into 1 cm pieces; skin it only if the stalks are particularly thick and fibrous.

Combine the orange flesh, rhubarb, and orange peel strips in a preserving pan and bring to a rolling boil over high heat. The initial boil — maintained for 30 minutes — breaks down the cell walls of both fruits and begins releasing pectin. You want the rhubarb to disintegrate almost entirely; the oranges will hold their shape better. The mixture will darken slightly as the fruit sugars concentrate. Add the 4 lb sugar once the fruit has softened and begun to collapse. Stir until dissolved, then reduce the heat to a gentle simmer.

The slow two-hour cook that follows is where caramelisation of the fruit sugars develops the preserve's depth. Stir occasionally to prevent sticking on the base — burnt fruit flavour is irreversible. Test for setting every 20 minutes after the first hour by dropping a teaspoon of hot preserve on a cold plate; when it wrinkles as it cools and doesn't run, you've reached the gel point. This is governed by pectin concentration and the boiling temperature of the mixture (105°C at sea level). Rhubarb is lower in natural pectin than most fruit, so some loss of liquid is essential; expect the preserve to reduce by roughly one-third of its starting volume.

When setting point is reached, remove from the heat and skim away any foam from the surface. Pour immediately into sterilised jars — the hot preserve must go into pre-heated glass to avoid thermal shock. Seal while the preserve is still hot. The preserve will reach full gel within 24 hours as it cools and the pectin network sets fully.