Rinse and peel potatoes, cut into bite-sized cubes. Peel and finely chop garlic and ginger. Heat oil in a large frying pan and sauté garlic and ginger. Add coriander, cumin, turmeric and cayenne and stir in garam masala.
Add potatoes, pour 300 ml (approximately 1 1/4 cup) of water and bring to a boil. Turn down the heat, cover and simmer on low heat for about 20 minutes. Add peanut butter and peanuts, cook for another 5 minutes. Season with salt and cayenne pepper. Serve.