If I recall correctly this is a recipe I have adapted from a Madhur Jaffrey version. It produces a fragrant dish of golden/red potatoes and is delicious.
2 large potatoes, peeled and cut into cubes
2 cloves garlic chopped fine
2 cm square knob of fresh ginger chopped fine
1 tsp mustard seeds
1 tsp cumin seeds
1 tsp turmeric
2 tsp tomato puree
Put the potatoes into a saucepan, cover with water, add turmeric, bring to the boil and cook for 10 minutes. Drain and set to one side.
In a mortar & pestle mix the garlic and ginger with a pinch of sea salt and grind to a paste.
In a frying pan heat over medium heat put 1 tbsp groundnut oil. When hot add mustard and cumin seeds and wait until they start to pop. Add garlic/ginger paste, stir and then add potatoes. Turn heat to low and leave to cook, stirring only occasionally, for about 15 minutes until the potatoes are cooked through.
About five minutes before serving mix tomato puree with 1 tbsp water and add to frying pan. Stir to coat. It will evaporate or be absorbed pretty quickly and once ready tip onto a shallow dish, sprinkle some sprigs of fresh coriander and serve.