450 g/1 lb. old potatoes
3/4 tsp. tamarind concentrate or 1 1/2 tbsp. lemon juice
150 ml/5 fl. oz. hot water
2 cloves garlic, peeled and crushed
1 tsp. salt or to taste
1/2 tsp. chili powder
1 tsp. paprika
4 tbsp. cooking oil
1 tbps. black mustard seeds
1 lg. onion, finely chopped
1 1/2 tsp. ground coriander

Put the potatoes in a 2-pint bowl or casserole and add 4-5 tablespoons hot water. Cover with a lid or cling film. Puncture the cling film and cook on high for 3 minutes. Turn the potatoes over, re-cover and cook on high for a further 3 1/2 minutes. Stand for 5 minutes.

Immerse the potatoes in cold water and allow them to cool completely; or cook the potatoes in advance and leave them in the refrigerator. Peel and cut the potatoes into 1-inch cubes.

Put the tamarind and the water into a 2-pint bowl or casserole and cook, uncovered, on high for 50 seconds. Stir and mix thoroughly, then add the garlic, salt, chili powder and paprika. Cover and cook on high for 45 seconds. Add the potatoes and cook, uncovered, on full power for 3 minutes, stirring halfway through.

Preheat a microwave browning dish for 4-5 minutes on high. Add the oil and heat on high for 1 minute. Add the mustard seeds. Cook on high until they start popping, 30 seconds to 1 minute. Add the onions.

Cook on high for 4-6 minutes until golden brown, stirring after each minute. Add the coriander; stir and cook on high for 30 seconds. Stir this mixture into the potatoes.