My mother is the queen of transforming leftovers into new wonders, and she comes into her own on Boxing Day, the biggest leftovers challenge of the year.

Christmas, after all, is a game of two halves. The first is Christmas Eve and Christmas Day (which I covered in last week’s Food Special), when there are plenty of fresh ingredients, bright-eyed cooks and extravagant feasts. Then, on Boxing Day and beyond, the kitchen turns into a battleground of odds and ends: pyramids of roast parsnips and spuds, Tupperware as far as the eye can see, when all you want is something that will virtually cook itself.

For my mother, using up leftovers was an obsession born of necessity, and she never threw out anything unless it was growing legs and about to walk out by itself. Now, spinning meals out of lonely and lost ingredients is her own one-woman game show, one that gives great joy as another piece of broccoli is saved from the bin. Her past Boxing Day triumphs include: roast potatoes hard fried with tinned chickpeas and lots of chilli and lemon; sprout and spud curry; pav bhaji, a sort of Indian bubble and squeak, piled high into yorkshire puddings; sweet and crunchy carrot and cabbage pakoras with a fiery cranberry chutney.

Today’s recipe is a homage to one of Mum’s Boxing Day curries. It’s Thai, not Indian, and not dissimilar to a red curry; but it features more aromatics such as Thai basil, kaffir lime leaves and galangal, and it comes together very simply via a blender and a pan. The result is at once soothing and enlivening, a meal that even the most tired cook can muster up without too much effort.

Christmas veg Penang curry
A perfect home for leftover roast veg, but salt judiciously, because they’ll have been seasoned already. (If you’d like to roast veg specially to make this, you’ll need about 1.4kg mixed potatoes, parsnips, carrots and sprouts, peeled and roasted in a little oil.) It’s worth hunting down fresh Thai basil, because it has a special aniseed flavour that really pulls the dish together. Serves four.

For the Penang curry paste
2 tsp coriander seeds
2 tsp cumin seeds
3 tbsp rapeseed oil
2 birds’ eye chillies, chopped
6 garlic cloves, peeled and chopped
1 banana shallot, peeled and chopped
2 sticks lemongrass, tough outer leaves removed, chopped
6 kaffir lime leaves
1 tbsp galangal paste (I use Bart’s)
1 handful roasted unsalted peanuts
1 ½ tbsp tomato puree

For the curry
1.2kg leftover roast vegetables
400ml tin coconut milk
1 ¼ tsp salt
1 ½ tsp caster sugar
Thai basil, to serve

In a large frying pan, toast the coriander and cumin seeds until golden, then leave to cool. Put the spices in a blender with all the other curry paste ingredients, and blitz to a smooth paste, adding up to four or five tablespoons of cold water to help it along.

Put a large pan on a low heat, then add the curry paste, salt and sugar (if your cooked vegetables are pre-seasoned, just season to taste at the end) and cook out the paste, stirring, for about eight minutes, stirring constantly.

Stir the coconut milk into the paste mix bit by bit, and once the can is empty, fill it a third-full with cold water and add that, too. Leave the sauce to come up to a simmer, then stir in the leftover roast vegetables and leave to simmer and heat through for a few minutes. (If you’ve made the veg from scratch, they’ll still be hot, so stir them in at the last moment.)

Scatter over a handful of Thai basil leaves, check and amend the seasoning to taste, and serve hot with plain rice.