If you like your food spicy, this works well with some cayenne or ground red pepper.
Gently boil the potatoes in their skins in lightly salted water until done, about 25 minutes. Drain and set aside. (You can do this step the day before, and refrigerate the potatoes. I find that the texture is a bit nicer if the potatoes have had a chance to cool after being boiled.)
Heat the oil and butter. Add garlic and ginger and cook a few minutes, then add the onions, other vegetables and spices, and cook until the onions soften.
Add the potatoes and stir. Turn the flame down and cook until the potatoes are heated all the way through, probably about 5 minutes. Adjust seasoning and serve.