It's conventional wisdom that you should never eat sushi on Mondays. But that's the thing about conventional wisdom: It's not always right.

Some of the most delicious raw fish in the city is available every Monday at the East Village sushi den Jewel Bako. There, the group dinner classes taught by "sushi concierge" Trevor Corson will make sure your fish--and sushi knowledge--is as fresh as it gets.

Corson (pictured), the author of The Story of Sushi and The Secret Life of Lobsters, walks aficionados and connoisseurs-in-training through an authentic sushi meal, revealing the surprising history of the cuisine (did you know that tuna, salmon and eel are not traditional sushi in Japan?), plus etiquette tips that will help you impress your friends and--more important--the sushi chef in charge of your meal.

The Monday-night dinners are at 6:30 p.m. and require a minimum of six participants. The price ($75 per person) includes an appetizer, 10 to 12 pieces of sushi, and soup, but not drinks or gratuity for the restaurant staff. Advance reservations are required. For more information and to reserve a seat, visit sushiconcierge.com.

Jewel Bako, 239 E. Fifth St. (between Second and Third aves.); 212-979-1012