The Japanese love taco bowls. You can blame World War II, if you like.

The first taco joint in Japan was a place called Charlie's in Okinawa, founded in 1956 to cash in on homesick American soldiers. Charlie's specialized in beef tacos topped with tuna-Kewpie sauce, wrapped up in rice flour tortillas.

But by the '80s, those tacos had crossbred still further into taco rice bowls that became a staple of Okinawan island cuisine—mixing avocado, lettuce, cheddar, beans, tomatoes, sour cream and brown rice with yuzu salsa and Japanese meats like miso-flavored chicken or ginger beef. Call it a farther east Whole Bowl, trading Indian fusion spices for Japanese.

Mayumi and Ichiro Sato started serving up those Okinawan-style taco bowls in Beaverton in 2013, but they closed their shop the next year to help open Yama Sushi & Izakaya on Southeast Clinton Street. Well, they have their own place again—this time serving up taco bowls out of a cart called Richi's—Ichiro's nickname—in downtown Portland.

The ginger beef version is unfortunately an unhappy marriage of flavors, a taco salad with ginger dressing. But when spiked with Sriracha or togarashi, the miso chicken bowl can take on the propulsory addictive quality unique to hearty comfort fare, the same reward system that sends you to the bottom of a bowl of popcorn. In Richi's case, it can be pinned to the expertly cooked rice—slightly sticky, seasoned and a bit al dente.

(Aubrey Gigandet)
(Aubrey Gigandet)
(Aubrey Gigandet)
(Aubrey Gigandet)

Although the cart was designed as an introduction to the Okinawan taco bowl, the ramen Richi's introduced last September may be the real reason to return. The cart serves only white (shiro) and red (aka) tonkotsu pork bone broths—the difference being the addition of chili oil. In those generous $8 bowls, the eggs are soy-dipped and flavorful, the noodles are medium thickness and al dente, and the broth is salty, sweet and viscous with fatty depth. The chashyu is a weak point—a little chewy—but the aka broth is nonetheless a delicious treasure, a lovely pink-red depth charge brimming with chili-oil heat.

(Aubrey Gigandet)
(Aubrey Gigandet)
(Aubrey Gigandet)
(Aubrey Gigandet)

Richi's has stiff noodle competition in the neighborhood—Marukin and soon-to-open Afuri are within blocks—but it's great to see actual streetside ramen available late nights in downtown Portland. (The "midnight" ramen is served, perplexingly, only until 11 pm.) All we need are two stools under the cart awning and five beers in our belly. MATTHEW KORFHAGE.
Richi's, 432 SW 3rd Ave., facebook.com/richisdowntown. 11 am-3 pm and 4:30-11 pm Monday-Friday, noon-4 pm Saturday.