I was probably in my early twenties when this sauce first appeared on my culinary radar as 'vitello tonnato.' At the time, a plate of cold, thinly-sliced poached veal dressed with a chilled, runny tuna sauce didn't make a lot of sense, but I tried it anyway, and have been a fan ever since. I don't often serve it with the traditional veal, but ironically that's the only thing I don't serve it with. Tonnato sauce is tremendous as a spread and equally impressive as an all-purpose, all-world dip.