In a large saucepan, heat the oil and fry the pepper, cumin and mustard seeds, asafoetida, red chillies, curry leaves, turmeric and garlic until the chillies are nearly black and the garlic is golden brown.

Lower the heat and add the tomato juice, lemon juice, water and salt. Bring the soup to the boil, then simmer gently for about 10 minutes. Pour the soup into bowls, garnish with the chopped coriander and serve.