To prepare the beef, marinate it in plain yogurt with a cinnamon stick, some cardamom, cloves and a few drops of food colouring. Refrigerate overnight, and then cook in the pressure cooker or bake at 300F for 2 1/2-3 hours, or until very tender. Set aside until you’re ready for it.
To roast the potatoes, toss them in oil and roast on a baking sheet at 425F for 20 minutes, or until golden. Set aside.
In a large pot, heat a generous amount of oil and cook the tomatoes, tomato paste, garlic, ginger, cilantro, cinnamon, cardamom, cloves, peppercorns, salt and chili powder for about 20 minutes, stirring often, until the mixture thickens, darkens and looks separated. Add the fried onions, the beef and any juices that have collected in the bowl, the roasted potatoes and about 2 cups of water. Bring to a simmer and cook, stirring often, until the mixture cooks down and thickens, the onions turn soft and the sauce looks more uniform. Spoon out any whole spices and serve with rice. Serves 6.