Heat a kadhai or heavy-based, deep frying pan (skillet) over medium heat.
When hot, add 4 tablespoons ghee, then add the lentils and roast for about 4 minutes. Set the ghee aside in the pan.
Put the cumin seeds and peppercorns into a spice grinder and process until coarsely ground. Alternatively, use a mortar and pestle. Set aside.
Transfer the lentils to a pressure cooker, add 375ml / 13fl oz (1/2 cups) water and cook under pressure for 5 minutes. Set aside.
Or Alternatively, put the lentils and water in a pan, bring to the boil, then reduce the heat and cook for about 40 minutes, or until soft.
Heat the reserved ghee in the pan, then add the semolina (farina) and fry for about 1 minute, or until golden. Remove from the pan and set aside.
Add a further 2 tablespoons ghee to the pan and heat through. Add the cashew nuts for the garnish and fry for 1-2 minutes, or until golden. Remove from the pan and set aside.
Pour 1 litre / 1 3/4 pints (4 1/4 cups) water into the pan. Add 1 teaspoon salt, the grated ginger and bring to the boil, then reduce the heat and gradually add the fried semolina, about 2 tablespoons at a time, stirring vigorously after each addition to blend well and prevent any lumps.
Continue to cook, stirring constantly, for 8-10 minutes, or until the water is almost absorbed and the semolina is cooked.
Fold in the cooked lentils, then stir in the curry leaves, turmeric, the coarsely ground cumin seeds and peppercorns and a further 2 tablespoons ghee and remove from the heat.
Garnish with the reserved cashew nuts and serve.