Chef Steve Tam has done a marvelous thing to one of my favorite desserts, cheesecake. Because his new Gohan restaurant in Petaluma serves Japanese food, he's added green tea to the recipe, using a very special nonbitter variety from Sendai, north of Tokyo. The fragrant leaf imparts a delicate, earthy flavor, enhanced by an ample dusting of powdered green tea over the top.

But he's also replaced the usual, humble cream-cheese filling with fromage blanc, making this confection incredibly light but rich, a bit tangy-sour and just a hint nutty. Can I lick my plate in such a nice setting as this, a sleek, sophisticated ambiance of polished wood, exposed duct ceilings and Japanese shoji-style accents?

Tam has put an interesting twist on wakame (seaweed) salad ($6) at his three month-old restaurant set in the Redwood Gateway (Kohl's) shopping center. He mounds the electric-green algae in a martini glass, tops it with a big scoop of fresh snow crab and a dollop of black caviar. It's important to get a bit of each ingredient in each bite; the mix is wonderfully crunchy and tender, sweet and salty.

I'm not expecting what I get with my kryptonite sushi roll ($14), either, which from the menu listing appears to be a typical rainbow recipe. Except that here the tuna, hamachi and salmon are tucked inside the rice with cucumber, daikon sprouts and avocado, instead of laid across the top, and the whole is slathered in crunchy tobiko. The fish is gorgeously fresh and silky--the best I've had in any Sonoma County sushi joint--and even the wasabi seems to burn hotter and better than at other local places I've tried.

Gohan also serves up a nice range of adventurous sashimi, with velvety ankimo (monkfish pâté, $10), hamachi carpaccio drizzled in sweet Banyuls wine ($12) and firm bonito slicked with wasabi-onion sauce ($12). Sorry, though, I can't bring myself to try the wacky Napoleon Dynamite ($13), a tempura roll stuffed with eel, cream cheese and snow crab, garnished with tater tots.

I'm a huge fan of nabeyaki udon ($15), and Tam's version is a satisfying success. The broth is light and savory over fat, slippery noodles and floating with properly rubbery fish cake, shiitake, scallion, tofu, Napa cabbage and a raw egg that slowly cooks in the steaming soup.

It's a meal all on its own, but for opulence I add an order of the "Over the Top" seafood tempura ($18) to dip in the broth, delighting in a lightly battered whole soft shell crab, prawns and scallops.

The tonkatsu ($14) was a bit dry, but that was easily remedied by dressing the panko-breaded pork with the excellent homemade tonkatsu sauce alongside. The entrée comes with miso (studded with tofu and shiitake), sunomono--the traditional chopped cabbage salad--spring greens and rice.

As Tam stops by my table after the last plate has been cleared (he's been making the rounds throughout my meal, greeting every single guest), he asks if there's anything he can do to make my experience even better. I can't imagine what, I tell him sincerely. Because what he's doing with Gohan is a wonderful thing indeed.

Gohan, 1367 McDowell Blvd., Petaluma. Open for lunch and dinner Monday-Saturday; dinner only, Sunday. 707.789.9296.

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