The 2 1/2-pound "Dirk Nowitzki" beef tenderloin served at Nick & Sam's may be the most decadent steak in the city, right up there with the 240-day, dry-aged prime steaks at Knife and the tomahawk ribeye slathered in foie gras butter at Three Forks. But don't look for it on the menu. It's not there, though you can order it any night.

Water Grill makes a whole fish ceviche-style. (Vernon Bryant / Staff Photographer)

And don't search for the duck wing chicharrones spiced with Peruvian chiles, then crisp-fried in blue corn tempura at Flora Street Cafe, or the ceviche-style whole fish at Water Grill either. Like the 41-ounce, $240 Dirk Nowitzki steak -- whose weight matches the Mavericks player's jersey number -- the duck wings and the market-price fish are insider secrets, sneaky pleasures for in-the-know regulars but available to the rest of us once we've learned the password.

"We started out serving them as part of the chef's tasting menu, but people who are adventurous eaters learned about them and now ask for them," says Flora Street chef and owner Stephan Pyles of the duck wings ($12) served with a fiery, tangy "Buffalo wing" sauce and a dollop of finger lime caviar.

The duck wing chicharrones at Flora Street Cafe are served with a fiery, tangy "Buffalo wing" sauce. (Rose Baca / Staff Photographer)

"Guests love to order something off the menu," says Samir Dhurandhar, chef and co-owner of Nick & Sam's, who created the 41-ounce bone-in fillet to honor the Mavericks player, a frequent customer at the steakhouse. "Half of our menu feels like it's part of a secret menu, but it's one more reason we give customers to return."

The $240 Dirk Nowitzki steak's weight matches the Mavericks player's jersey number. (Rose Baca / Staff Photographer)

Secret menu dishes sometimes begin as special requests or occasional features but unexpectedly gain VIP status. At Pappas Bros. Steakhouse, for example, insiders know to amp up the already decadent mac and cheese by adding big chunks of crab for $16.95 or sweet Maine lobster for $17.95.

The mac and cheese at Pappas Bros. Steakhouse can be made with crab or lobster. (Tom Fox / Staff Photographer)

Velvet Taco swapped value for decadence to popularize its off-menu "back door" chicken deal. The taco joint sells a rotisserie-roasted chicken, fresh corn tortillas, corn elotes and pico de gallo, all packed for carryout, for $20. On Mondays, though, insiders know to skip the line and head instead to Velvet Taco's back door. Rap on the door, hand the person who answers a $10 bill, then walk away with that same chicken dinner for half-price. The nearly silent exchange goes down like an illicit drug deal -- but with none of the risk and all of the reward.