But while the crawfish business is booming, Tran was surprised to find that Houston's Vietnamese population was not enthusiastic about other Cajun dishes -- like the gumbos and étouffées she learned to make while working at a restaurant in New Orleans.

Judging by the empty dining room at Epoch Fusion Café (1915 Westheimer) one recent lunchtime, mainstream Houston diners haven't really taken to Vietnamese-Cajun food either. Epoch also is owned by a Vietnamese-American from Louisiana. The hors d'oeuvres list includes chicken wings, fried crab claws, Saigon egg rolls and duck spring rolls; entrées include Creole snapper, bacon-wrapped shrimp, ginger crispy duck and poached Oriental chicken. I sampled a bowl of Cajun chicken sausage gumbo, which was quite good, if a little underspiced. I also had a shrimp poor boy, with grilled shrimp that had been marinated in a soy sauce mixture.

The idea of making poor boys with grilled Asian-style shrimp instead of the usual fried stuff is a brilliant innovation. I would have loved to recommend the Asian shrimp poor boy as a Vietnamese improvement on Cajun cuisine -- if only the bread had been better. Instead of the toasted Vietnamese mini-baguette we take for granted on $2 bahn mi thit (Vietnamese sandwiches), Epoch Fusion Café serves the fabulous shrimp on something that tasted like an oversize hot dog bun. Evidently, there are still a few bugs to work out in Vietnamese-Cajun fusion.

The truth is that the owners of these restaurants are simply serving Vietnamese and Cajun foods side by side, the fusion occurring incrementally and mostly by accident -- crawfish finding their way over to the fried rice. It's actually quite a natural process. The two cuisines have a lot in common. Rice is the basic staple of Vietnamese and Louisiana cookery, and both rely heavily on fresh seafood and chile peppers. And since both were also once French colonies, they speak the same language in the kitchen; baguettes, beignets and café au lait are as well known in Saigon as in New Orleans. Poor boys and bahn mi thit are remarkably similar, despite the fact that they evolved half a world away from each other.

The Asian-Cajun connection also raises some fascinating issues about the evolution of Gulf Coast ethnic communities. "Food traditions are particularly intriguing because they are some of the most persistent of traditions," writes Louisiana cultural anthropologist Maida Owens. "As a result, food often becomes closely tied to cultural identity and can reveal cultural processes such as blending, diffusion or maintenance."

Louisiana gumbo, with its African, European and Native American elements, is a prime example of the cultural blending process called creolization, says Owens. Tex-Mex, the hyphenated offspring of two distinct cultures, is what scholars call hybridization. But Vietnamese-Cajun fusion is something different. According to one expert, it's a clear case of syncretism, a word anthropologists use to describe the absorption of one culture's traditions by another.

The Vietnamese, who were under Chinese rule for a thousand years and a were French colony for 150, have a long tradition of culinary syncretism, says Carl Bankston, an associate professor of sociology and Asian studies at Tulane University. Pho, for instance, is an adaptation of Chinese noodles, but now it's as Vietnamese as it can be. The Vietnamese baguette, with its component of rice flour, is a distinctly Vietnamese version of French bread. The Vietnamese have learned to adapt to outside domination by taking foreign influences and making them their own, says Bankston. And the results of these innovations are authentically Vietnamese.

"But why is it that while Mexican and Chinese restaurant owners watered down their cuisines to suit American tastes, Vietnamese restaurant owners seem to be going in the opposite direction, opening restaurants that appeal to fellow Vietnamese-Americans?" I ask.

For one thing, the Vietnamese community is very large, big enough to support a lot of restaurants, he explains. But the other reason has to do with employment patterns: According to Bankston, many Vietnamese came to the Gulf Coast to seek employment in the seafood industry -- and they continue to be disproportionately employed in fishing, shrimping and seafood processing.

Unlike Chinese and Mexican immigrants, the Vietnamese typically did not support themselves by opening restaurants. Because they didn't have to appeal to mainstream customers, they did not dilute their cuisine as much. "It's the same with Vietnamese-Creole food," he says. "It's designed to appeal to new generations of Vietnamese. It's not a watered-down cuisine for the American palate."

I tell Bankston about the Vietnamese crawfish dipping sauce and ask him if he's ever seen it in Louisiana. "No," he says, "but Louisianans make a dipping sauce for their oysters. And everybody has their own combination of horseradish, lemon, ketchup and so on. Maybe the Vietnamese saw the locals making oyster dips and tried the same thing with crawfish."