Bay Area eaters are eagerly gulping down Vietnamese noodle soup, or pho, typically made with beef or chicken broth. Turtle Tower in the Little Saigon neighborhood is one of San Francisco's dozens of pho restaurants. Stephen Pham, the owner, came from Hanoi 20 years ago to what he calls "the land of opportunity."

Kevin Le dines on Pho Ga Long, Chicken Noodle Soup with Chicken Giblets, at Turtle Tower Restaurant in the Tenderloin on Wednesday, September 29, 2010

Pho Fever

Some culinary experts speculate that the word "pho" may come from the French "pot-au-feu," or beef stew, which literally means "pot on the fire." In Vietnam, pho is primarily eaten at breakfast.

Northern Namesake

Turtle Tower restaurant is named after a famous Hanoi landmark, Thap Rua, a three-level pagoda built in the 1800s in the middle of a lake. Pho was created in North Vietnam, and Turtle Tower's soups stick to the original style: they are served with green chilies and limes, but without the bean sprouts, basil and hoisin sauce that were added when the soup migrated south in the 1950s.

Simmering Slowly

Turtle Tower boils its pho broth for 10 to 15 hours. One of its most popular dishes is pho ga long (chicken noodle soup with giblets), which uses free-range chicken, freshly made noodles and vegetables from local farmers markets.

Gut Buster

Pho Garden on Clement Street offers a challenge: Anyone who can swallow the contents of a gigantic bowl containing two pounds of noodles and two pounds of beef in 60 minutes gets the meal, normally $22, free. Photos of some 140 successful gluttons are displayed on the restaurant's "Pho of Fame" wall.

Phun With Pho

Pho is pronounced "fuh" -- like "foot" without the t. Pho fans employ many puns in their praise: phocused, phonatics, photastic, pho fix, phogasmic, what the pho?, and un-pho-gettable.

Do We Dare?

In addition to beef slices, beef tripe, tendon and meatballs are optional ingredients preferred by many Vietnamese customers. Tripe is stomach lining; tendon is tough, gelatinous and translucent; the meatballs sometimes contain cartilage and tendon.

Local Scholar

Charles Phan, owner of The Slanted Door, the celebrated Vietnamese restaurant in the Ferry building, researched pho in Hanoi in the 1990s and found chefs who added aromatic oil from a male beetle gland to the soup.

This article also appeared in the Bay Area edition of the New York Times.