Here's what you think you know about caviar: Beluga is better than sevruga and you serve it with toast. Not so, say the leaders of the monthly caviar workshops at Petrossian in New York. Beluga is prized mainly because it's easy to pronounce and it should be eaten alone. The two-hour seminar sets the record straight on all issues surrounding this delicacy, weaving together history, cooking techniques, and, best of all, tasting notes. In addition to the main varieties, participants sample transmontanus, a terrific up-and-coming caviar farm-raised in California. Seminar, $290. At 182 W. 58th St.; 212-767-1041.