In a large heavy non-stick skillet heat butter over moderate heat until foam subsides and cook spices, stirring, until fragrant, about 1 minute. Add eggplant and salt and toss to coat with spice mixture. Stir vinegar mixture and add to eggplant mixture. Simmer mixture, covered, without stirring, 10 minutes, or until eggplant is just tender. Uncover skillet and cook eggplant mixture at a rapid simmer, without stirring, until liquid is almost evaporated and eggplant is slightly charred (but not burned) on bottom, about 15 minutes.