Bolognese sauce seems simple enough: a little meat (chef's choice), some tomatoes, olive oil or butter (or both), garlic (maybe), wine, seasonings and a secret ingredient or two. Yet in the wrong hands, this sauce can go awry. Not so at Caffe Milano, a fine little spot downtown. Here, all the ingredients come together in a most delightful way. Served with tagliatelle, this traditional Northern Italian dish sings. Fortunately, the dish is available for lunch (weekdays) and dinner (Friday and Saturday only from 5:30 to 9:30 p.m.), so you can enjoy a glass or two of good red wine with it.