This sturdy delight formed the backbone of one of our most memorable dinner parties. We served it with potato pancakes, homemade apple sauce, sweet and sour red cabbage, and apple strudel, giving our guests the choice of Dos Equis, Mexico's magnificent amber beer, or Charles Krug's Zinfandel (uncorked a few hours before serving). Some guests had both! The trick is to marinate the meat a long time, at least 10 days, and turn it twice daily. The sauce that emerges from the pot after cooking is something your guests will be talking about for days.