1. Combine the lentils and water in a heavy pan. Bring to a simmer. Remove any scum that collects at the top. Add the ginger and turmeric. Stir to mix. Cover, leaving the lid very slightly ajar, turn heat to low and simmer gently for 1.5 hours or until the lentils are tender. Stir every 5 minutes during last 30 minutes to prevent sticking. Add the salt and stir to mix. Remove the ginger slices.

2. Put he oil in a small frying pan and set over medium heat. When hot, put in the cumin seeds. Let the seeds sizzle for a few seconds. Now put in the ground coriander and cayenne. Stir once and then quickly pour the contents of the frying pan (the oil and spices) into the pan with the lentils. Stir to mix.

3. Sprinkle fresh coriander over the top when you serve.