DRIVING TO WORK during the big rainstorm two weeks ago, it hit me like a sheet of water from a passing big rig: I must have soup. It's a culinary cliché, but when it's wet and dreary I start thinking of soup. Properly motivated, my next task was to figure out just what kind of soup. My first thought was a steaming bowl of pho, pho being what I think is Silicon Valley's most distinctive dish. But that would be too easy. The Vietnamese beef noodle soup is rightly beloved, but I decided to explore some lesser-known Vietnamese soups, known as canh.

To make it even harder I ruled out pho ga (chicken noodle soup) and bun bo Hue, too. Bun bo Hue is pho's spicier, central Vietnamese cousin. It's a great soup, and I actually prefer it to pho, but it and pho ga should be pretty familiar to anyone who spends time in Vietnamese restaurants. I wanted to go further afield in my search for Vietnamese soupy goodness. So over the course of the next few days, I began my soup search.

And yes, last week I reviewed Santouka, a new ramen restaurant, so you might ask what the deal is with all the Asian noodle soups. What can I say? I like the soupy noodles. So without further ado I'd like to introduce you to hu tieu, mi quang, bun rieu and the beguiling cha ca thia la.

Hu Tieu (pronounced "who tee-u") is a huge class of noodle soup. At its most basic, the broth is made from pork bones, but without the distinctive flavor of fish sauce that pervades so many Vietnamese dishes. The noodles can be made from rice, tapioca or eggs, but the hu tieu noodles are always thin like vermicelli. What's in the soup is where things get unpredictable.

Sliced pork or ground pork is common, as is seafood. I spooned into a noteworthy bowl of hu tieu at Ca Mau, a first-rate restaurant in southeast San Jose. Story Road was the epicenter of the Little Saigon dustup last year and is generally thought of as the heart of San Jose's Vietnamese community, but traveling southeast down White, Tully and Quimby roads reveals a gold mine of Vietnamese restaurants of every kind imaginable. That's the area where I found Ca Mau. The restaurant is noteworthy not only for its hu tieu, but for its gorgeous floor-to-ceiling mural depicting farming, rice paddies and fishing scenes in Vietnam.

As for the hu tieu, the house special is the mi ca dac biet ($6 small, $6.95 large). The dish translates as "special Chinese egg noodle with fish and just about everything else." In this case, that means sliced pork, ground pork, squid and whole shrimp.

Just as hamburgers are served with lettuce, onions, tomatoes and pickles, Vietnamese soups are all served with a particular set of garnishes. It may look like a haystack of lettuce and herbs, but there's quite a bit of variability depending on the kind of soup. Hu tieu traditionally comes with chives and Chinese celery, the pungent leaves and ribbons of the crunchy stalk. You also get the standard bean sprouts, basil leaves and jalapeños. The chives were already sprinkled on top, and I added a handful of celery and basil leaves, and it really brought the flavorful broth to life. A spoonful of the superb chile–lemon grass paste set out on the table makes this satisfying soup even better. I liked it at the first spoonful, and it got better from there.

My new favorite soup is mi quang ("me kwan"). What sets this central Vietnamese–style soup apart is the striking, taxicab-yellow color of the wide egg noodles and the broth that comes from the addition of turmeric. It's also served with a dusting of ground peanuts and a crisp rice cracker flecked with black sesame seeds. The amount of broth served with the soup ranges varies from place to place. I like a wetter version myself.

The first place I had this distinctive soup was My Khe Quan Hue. Here the voluminous bowl ($6.50) is sprinkled with ground peanuts as well as fried shallots and loaded with slices of mild fish cakes and pork. The broth has a clean, refreshing flavor.

Another good source for mi quang is Pho Yen. The simple but clean restaurant is best known for its pho, but the mi quang ($7) is great. In addition to sliced pork, shrimp and squid, the soup floats two quail eggs with perfectly soft-cooked yolks. The nutty, rich broth had me spooning way past the point of full.

With a full belly of Pho Yen's mi quang, I pointed my car toward one of San Jose's two greatest one-stop shops for Vietnamese food—Story Road's Grand Century Mall. (The other one is Lion Plaza on Tully Road.)

Bun rieu is another of my favorite soups and Pho Phi Long, a fluorescent-lit, Formica-table spot next to the mall's row of food stalls, is the place for it. Bun rieu is made from thin rice noodles and ground rice-paddy crabs formed into savory little balls, but in the American restaurants they sometimes have to use other kinds of crab. The soup ($6.95 small, $7.95 large) is enlivened with tomatoes to give it a sharp, pleasingly acidic bite that tempers the richness of the crab and the addition of fried soft tofu. The unsmiling servers are brusque, but I didn't care as soon as I got the soup.

My final stop on my Vietnamese soup tour was Nha Toi, a San Jose restaurant that specializes in elegantly prepared northern Vietnamese food. Although pho is a national dish in Vietnam, northern Vietnam is where the soup originated. So naturally, when I pointed to the falling rain and said I was in the mood for soup, co-owner Susie Bui directed me to pho. When I explained my interest in soups other than pho, she thought for a minute and suggested cha ca thia la ($7.95). She picked a winner.

The northern Vietnamese soup is based on chicken broth, but the star ingredients are lightly fried fish balls and a fistful of fresh dill. We don't eat enough dill. It's a refreshing, distinctive herb that pairs really well with fish. The soup has a tangy, fresh quality that's really set off with the addition tomatoes and green onions. My yen for a rainy day bowl of restorative, warming soup was fully satisfied.

CA MAU

2847 S. White Road, San Jose; 408.532.8989.

MY KHE QUAN HUE

960 Story Road, San Jose; 408.920.9603.

PHO YEN

974 Lundy Road, San Jose; 408.259.2112.

PHO PHI LONG

1111 Story Road, San Jose; 408.282.1666.

NHA TOI

460 E. William St., San Jose; 408.294.2733.

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