Prue Leith served up a tasty Vietnamese sweet and sour soup with shrimps and pineapple on Saturday Kitchen.

The ingredients are: 2-3 tbsp vegetable oil, 2 small tomatoes, preferably slightly unripe, peeled and quartered, 2 tbsp nam pla (fish sauce), 2 tbsp lemon juice, 2 star fruit, preferably slightly unripe, thinly sliced, 1 small pineapple, preferably slightly unripe, peeled and cut into chunks, ½ tsp freshly ground black pepper, 2 tbsp tamarind paste, 1-2 tsp sugar (to taste), 500ml chicken stock or ready-made fresh chicken stock, 3 spring onions, including green parts, sliced thinly, 1 kg raw king prawns, shelled and de-veined, 1 large handful fresh coriander leaves, roughly chopped and 1 fresh long red chilli, seeds removed, sliced thinly.