I go through a box of clementines the evening I bring it home

In winter, clementines come home by the box: a wooden crate or a big net bag, bright orange, with a few dark green leaves still attached. It is one of my favourite things about the cold months. But a box of fruit is a box of fruit, and if one clementine at the bottom is soft or mouldy, in a few days, the ones touching it will be too. So the evening I bring a box home, before anyone starts eating, I go through it.

I tip the clementines out onto a clean tea towel on the table, gently, a few at a time, and look at each one. A good clementine is heavy for its size, firm with a little give, and has a shiny, tight skin. I sort them into three groups as I go.

The first group is the perfect ones. These go back into the box or into a wide bowl in one layer, not piled high, so the air can reach them. I keep them somewhere cool, away from the radiator and the oven, and away from direct sun. A cool room or a cold windowsill is fine for a week or so. For longer, I keep some in the fridge, in the salad drawer, where they stay juicy for two weeks or more.

The second group is the ones with a soft patch, a small bruise or a scratched skin. They are fine to eat, but they won't keep, so they go into a separate bowl on the kitchen table to be eaten first, over the next day or two. If the children reach for a clementine, I point them to that bowl.

The third group is anything with mould: a white or blue-green fuzzy patch, or a skin that is wet and sunken. These go straight into the food waste, not on the compost pile with the good peel. I don't try to cut the mouldy part off a citrus fruit, because the mould spreads into the soft flesh. And I look very carefully at any clementines that were touching a mouldy one. If they look and feel clean, I wipe them with a dry cloth and put them in the "eat first" bowl.

I also check the box itself. If there is mould on the paper or the wood at the bottom, I throw the paper away and wipe the box before the good fruit goes back in, or I just use a bowl instead.

Then the fun part. Clementines are wonderful as they are, peeled at the table, but I use them in the kitchen too. I wash them under warm running water before using the zest, because the skin has been handled all the way from the tree to the box. Grated zest goes into cake and biscuit dough, into a crumble topping or a pot of cranberry sauce. Segments go into a winter salad with beetroot or into yoghurt for breakfast. And one of my favourite little things is clementine sugar: the zest of two clementines rubbed into a jar of sugar with my fingers, which smells of the festive season for weeks and is lovely in tea or on pancakes.

Clementines are a citrus fruit, and some people react to citrus, so I mention it when there are guests. For very young children, I take off the white pith and cut the segments into small pieces, as whole segments can be a choking risk.

The peel I don't throw away straight away either. A few pieces dried on a plate near the radiator make the whole kitchen smell lovely. My New Year clementine starters are the dish I make when the box is still full. Do you go through a box of fruit when you bring it home, or only when you find the first soft one?

Clementine sugar. Makes 1 small jar. About 5 minutes. You need 2 clementines and 150 g caster sugar. Wash the clementines under warm running water and dry them. Finely grate the orange zest only, not the white pith, straight into the sugar. Rub the zest into the sugar with clean fingers until it is fragrant and slightly damp. Spread on a plate for an hour to dry, then keep in a clean, dry, closed jar for up to a month. Use in tea, on pancakes or in baking.