The bones of this sauce is below, however you must feel free to make this for your own palate, if you like it hot then add more curry powder.  Also, different brands of tomatoes have slightly different acidity so you may need a little more sugar.  Leftover chakalaka is really lovely on toast with a fried egg 

Ingredients
1 tbsp oil 
1 large onion, finely chopped 
1 tbsp curry powder, we used 2 tsp of medium Raja powder and 1 tsp of hot Raja powder 
1 tin (400g) crushed tomatoes 
1 tin water (use the empty tomato tin to pick up all of the tomato juice) 
2 tbsp Mrs Balls chutney 
1 tbsp Worcestershire sauce
1 tbsp home made peri peri or other hot sauce 
1 tsp sugar 
1 tsp Salt 
½ tsp ground black pepper

Method
Heat the oil in a large saucepan and gently fry the onion over a medium heat for 5-7 minutes until soft and translucent - you don't want any colour on the onions.

Add the curry powder and cook for a minute. Add the tomatoes, water, chutney, Worcestershire sauce, the peri peri sauce, stir and add some sugar, salt and pepper and stir again.

Leave cooking for 45-60 minutes then check the balance and seasoning, you may need to add a little more sugar or salt.

Serve when you are happy with the balance.