Boil the potatoes until they are fully cooked, making sure they do not break.
In a mortar and pestle grind the cumin seeds with the garlic.
Heat the oil in a frying pan.
Add the garlic and cumin paste, tomato paste, lime juice, salt, basil, and sugar until the oil separates.
Add the water and stir.
Add the potatoes and toss. Reduce heat, cover and simmer for about 5 minutes.
Garnish with basil and serve.