Why would people want to put vinegar on ice cream? Would that not curdle it? It curdles milk. I am a bit lost on this one. Can some of you chef types explain this so I can understand it?
No one would put vinegar on ice cream. That would be silly. The confusion comes from people who think balsamic vinegar is vinegar, and you would want to put balsamic vinegar on ice cream, especially strawberry or vanilla ice cream. But, there is more than one kind of balsamic vinegar. For ice cream (and strawberries, peaches, grilled fish, steaks) you want the high dollar Traditional Balsamic Vinegar (Aceto Balsamico Tradizional). If it says "Balsamic Vinegar of Modena" then it's a commercial grade condiment, fine for salad dressings, sauces and dips, but it's not the same as the traditional, artisan stuff.
The traditional balsamico is made from a cooked reduction of pressed Trebbiano Lambrusco grape juice (grape must). It's a very sweet syrup, which is then allowed to ferment (like regular vinegar) and is aged a minimum of 12 years, the longer the better, and the more expensive. The initial reduction is about 30% of original volume. The more it ages the more it reduces and concentrates the flavors. It's sweet and sour and all kinds of stuff at once. If you're very rich, it's the perfect end of a meal to take a sip or two right out of a small glass. But a couple of drops on the tongue will suffice.
The grocery store balsamic vinegar (almost always Balsamic Vinegar of Modena) is red wine vinegar (what you know as vinegar) mixed with caramel color, sweeteners, and thickeners to make it imitate (badly) the taste of the Traditional Balsamico.
My favorite is a 50 year old Aceto Balsamico Tradizional de Modina by Pedroni of Italy. A 250 ml bottle (1/4 of a liter, about one cup) is about $500 a bottle ($479 at Amazon). I also have a Cavalli Reggio Emilia 75-year, Gold Seal, 100ml bottle (3.4 ounces) that I received as a gift. It's about $300 for the 100 ml bottle. Both bottles come with an eye dropper thing to dispense it, because one drop goes a long way.
If you find even a Traditional balsamic that's under $50 for an 8 ounce bottle, use it for salad dressings or a reduction sauce for cooking. You want at least 25 years aged and at least $100 for 8 ounces (250ml), but more likely two or three times that amount of money for the good stuff.