I adapted this from the recipe on the BBC’s Hairy Bikers site. There’s a milder alternative on the nipitinthebud blog, from the River Cottage Preserves Handbook
Traditionally, piccalilli contains a mixture of vegetables – cauliflower, courgette, small onions, maybe turnip or sweet pepper. I’ve made it with only carrots and sliced cooking onions, which are often on the supermarket cheap shelf, and am happy with the result.
2 or 3 onions
1 heaped dessertspoon English mustard powder
1 heaped dessertspoon ground turmeric
1 heaped dessertspoon chilli flakes or powder
1 heaped teaspoon cornflour or plain flour
Chop the vegetables into your required size chunks. Put in a bowl in layers, sprinkling salt over each layer as you go. Cover and leave for 24 hours.
Run the bowl under the tap, swishing the salted veg around, drain then run the tap through them again. Set aside.
Slice onions thinly, put in a large pan, barely cover with cider vinegar and simmer for 15 minutes.
Mix mustard powder, chilli, turmeric and flour to a thin paste with vinegar, set aside for flavours to develop as the onions simmer.
Add drained veg to onions, add vinegar to barely cover again and return to simmer for 10 minutes.
Add spice mix, stir well and leave to simmer for final 10 minutes, stirring occasionally to prevent sticking (one tiny burnt bit will taint the whole batch).
Put in jars and leave for a month for flavours to develop and to take the edge off the vinegar. The above made a litre.
I made a batch 2 weeks ago, sampled it as this was cooking and it’s still a bit harsh, but I can tell it’s going to be scalp-tinglingly delicious. If you prefer less heat and bite, try the version on nipitinthebud