Steam or boil the potatoes until they are just cooked but not breaking up. Drain well and set aside.
Heat the oil and butter together in a large frying pan or wok over a medium heat. Add the garlic and ginger and stir around for 1 minute, then add the ground cumin and caraway seeds and stir for another minute. Add the potatoes and sauté, stirring occasionally, over a medium heat for abo