Chilli and corn relish

I remember eating hamburgers from a takeaway on the Weymouth seafront when I was a student and the sweetcorn relish stuck in my mind. It came from a huge catering jar but there was something about it that gave the hamburger a real lift. Here's a version that you can try at home.

1 medium onion, peeled, halved and finely chopped
1 medium red chilli, finely chopped
a red pepper, seeded, halved and finely chopped
1tbsp vegetable or rapeseed oil
1tbsp cider vinegar
1tbsp granulated sugar
500ml vegetable stock
The kernels from 3 cooked corn on the cob
1tbsp cornflour
Salt and freshly ground black pepper

Gently cook the onion, chilli and red pepper in the rapeseed oil for 4-5 minutes until soft, add the vinegar and sugar and simmer for a couple of minutes, then add the stock and sweetcorn and bring to the boil. Dilute the cornflour in a little water and stir into the relish. Simmer gently for 15 minutes then take out and blend about one-tenth of the relish and return it to the pan, simmer for another 5 minutes, then leave to cool. Serve with a burger.