Money-saving chilli con carne

1tsp vegetable or olive oil

1 onion, finely chopped

4 garlic cloves, finely chopped

2 green chillies, finely chopped, plus 1 to serve

500g minced beef

41g packet of chilli con carne seasoning

400g tin chopped tomatoes

130g tin kidney beans, drained

300ml beef stock (made with a stock cube)

Salt and pepper