Lightly roast the cumin seed and coriander seed by frying with no oil for a minute or so, stirring constantly. Grind these and combine them into a paste with the other spices, the garlic, ginger and the vinegar. Add the lamb to the marinade and mix well. Refrigerate for 3-24 hours while mixing every few hours as convenient. Finely chop the onions and potatoes and saute them for 5 minutes in the butter. Add lamb and spice paste and simmer over low heat for half an hour. The marinating does add a lot of flavor and makes the meat much more tender. This can be skipped if need be. NOTES: * A spicy hot Indian lamb dish -Very loosely based on Dharamjit Singh's recipe in "Indian Cookery: A Practical Guide." Most restaurants that serve this dish pronounce it vinDAloo, with the stress on the second syllable. : Difficulty: easy (though it's easy to burn the spices while roasting them). : Time: 1 hour preparation, 1 day marinating, 1 hour cooking. : Precision: approximate measurement OK. : Nicholas Horton : Aiken Computation Lab, Harvard University, Cambridge, MA USA : horton@harvard.harvard.edu : Copyright (C) 1986 USENET Community Trust