The Find: Thien An Bo Bay Mon in Rosemead

When Vietnamese food lovers spot the neon sign of Thien An Bo Bay Mon, they know exactly what to expect at the Rosemead restaurant. Bo bay mon (often spelled bo 7 mon) denotes the famous Saigon-style all-beef dinners of seven courses, brought to the table one by one, each dish cooked by a different method.

Since the earliest days of Little Saigon, the fame of a seven-course beef specialty house like Pagolac or Anh Hong rose and fell on its mam nem, a pungent dipping sauce that for some is an essential part of the meal. Based on aged fermented anchovies (think Limburger cheese to the 10th power), it can be shockingly intense to the untrained palate. We would always request the more familiar sauce nuoc cham chua ngot.

At Thien An, the mam nem sauce is a world apart from those trés funky versions. “It’s the southern style,” says co-owner Lien Pham. “In the northern and central regions people prefer stronger saltier flavors.”

The subtle tart-sweet fruitiness comes from the addition of orange juice and the judicious use of fermented fish. If your waiter asks if you’d like a demonstration on how to mix the sauce, say yes to get the hang of how it can be customized. He’ll blend the house sauce base then add marinated sliced lemon grass, chile sauce and roasted minced peanuts to your liking.

Pham, her husband and her two brothers opened the original Thien An in Garden Grove in 1989, about a decade after the first of the bo 7 mon places. They credit its success in part to their proprietary sauce. Another branch was added in Westminster several years ago. This one, open a little over a year, is their newest venture.

The restaurant’s two large rooms are painted in a sort of trompe l’oeil cloudy sky motif and decorated with post-Louis XIV-era Fragonard-style genre paintings that seem to await a formal reception.

As extravagant as bo 7 mon dinners may sound, they aren’t so much bacchanals as a series of elegant little dishes.

First come the accompaniments: bowls of warm water and stacks of dry translucent rice papers for wrapping, then plates of cucumber, green banana spears, marinated julienned carrots and daikon. The dia rau song, or table salad -- one of the best I’ve seen in the San Gabriel Valley -- is so densely piled with fresh herbs it looks like the undergrowth in a rain forest. Included are lemon balm, red perilla, no gai (the saw-tooth leaves that taste like concentrated cilantro) and tiny rau om, known as the rice paddy herb.

The first course, shrimp and beef salad in a light lemony dressing, is followed by lean top round that you cook shabu- shabu style in a vinegary broth. It’s best wrapped with plenty of the herbs in moistened rice paper and dipped.

The fondue broth is replaced by a hot iron grill on which you sear beef slices marinated in lemon grass and sesame oil. Then come the best meatballs you’ve ever tasted, garlicky, salty and vaguely sweet followed by seasoned minced beef wrapped in la lot leaves (these resemble cooked grape leaves).

The sixth course, cha dum, a tennis-ball-size pâté of ground beef, mushroom and nuts is scooped up with crunchy shrimp crackers. And for the finale, a comforting bowl of beef-flecked rice soup with the alphabet noodles that for some reason seem to be included at every bo 7 mon restaurant.

It’s not all beef here though. On a crowded Saturday, more than half the diners have ordered the other house specialty, ca nuong da don -- very large whole catfish roasted until its skin is bronze and crackly. People are wrapping chunks of it in cool lettuce to dab into their mam nem.

If you come with more than four people you can easily try both beef and fish at the same sitting. The fish, available in three sizes ($35, $39 and $45), may take up to 30 minutes to arrive, during which time you can be happily engaged in eating the first of the beef courses.

Possibly the best thing about Thien An, besides its sauce, is the leisurely way eating here slows the pace of life with friends or family gathered around a communal meal. For $15 or so, that feels like a real celebration.

food@latimes.com