Koi Restaurant

Baby crab tempura. (Vicki Valerio / Philadelphia Inquirer)

Alex Park wanted a room that would convey the deep-fried heat of Kissen, the new tempura bar in Northern Liberties.

That is why, when you look through the welded-pane, glass-box facade of this North Second Street nook, you'll see a blaze of lipstick-red countertops and the glint of a copper-wrapped bar curling around the chefs as they sizzle, slice and fry. Even the restaurant's logo, cards and menus are stamped with a thermal reading, 269 degrees Fahrenheit - the threshold, Park says, at which his oil enters the frying zone.

The temperature drops considerably once you step inside. The colors may be hot, but the mood here is futuristic cool, complete with rubber floors and molded plastic chairs so sterile that I expected those hermetically sealed dancers from the microchip commercial to come waltzing down the aisle in their silver space suits. Or maybe something in latex from the bondage shop next door.

I prefer the glowing earth tones of Kisso, Park's charming sushi bar in Old City just a few blocks south. But perhaps the edgier look is well suited to Northern Liberty's uber-hipness. Either way, I know this restaurant makes a nice addition to the neighborhood's growing roster of intriguing eats.

Kissen, which Park co-owns with Leo Park, his childhood friend and speed-skating buddy from Seoul, bills itself as the city's first tempura bar. With the addition of a few Korean accents, it's just as much a sushi shop and noodle house as any other Japanese restaurant in town. But fried food is certainly what Park's crew does best.

Tempura is the world's most elegant crust, ice-cold batter fused in hot rice oil to a delicately pale crisp. At its best, it's a wisp of crunch and a translucent veil, the ultimate seal for flavor at its most natural. Thick rings of onion melt inside with sweetness. Asparagus spears snap open to reveal cores of vibrant green.

Kissen occasionally adds strands of potato and carrot to its mix, winding coils around plump, sweet shrimp or plugs of saline scallops. The sensation is intriguing, the crunch woven with an extra dimension.

But why distract from the simple elegance of a perfect batter and good ingredients? Kissen's best tempuras go without embellishment. Biting into a morsel of deep-fried sea urchin is its own amazing sensation, the sweet, hot, orange urchin cream melting into the minty green of the shiso leaf that cradles it. A squeeze of lemon and a pinch of Kissen's spicy salt add new layers of flavor.

A special of tiny sawagani crabs was another sensation. Imported live from Japan, these unusual freshwater crabs - no bigger than coins - were crisped, then posed over a nest of fried potato threads. We devoured them whole like crab-scented popcorn.

There are still a few kinks at Kissen. When it comes to maintaining tables or pacing a meal, the service is clueless, the servers bringing platter after platter whether or not there's room on the table. A full water glass is a rare commodity.

The reach of the large menu may exceed its grasp. I loved the Zen-like simplicity of the broiled yaki salmon entree, two luscious fillets set alongside a pouf of fresh spinach leaves dressed with sweet miso. But some other entrees were just too plain. The toro toban yaki was an unwieldy slab of grilled tuna belly that somehow lacked the lusciousness I expect when toro comes as a smaller piece of raw sushi. The unusual delicacy of broiled yellowtail jaw was a wing-shaped cut of fish that arrived moist but had a watery, dull flavor.

I also wish Park were less shy about presenting specialties from his native Korea. A few appear on the menu undisguised, such as the bi bim bap rice bowl laden with shredded beef and vegetables, and the tasty - though slightly doughy - pa-zun seafood crepe. A sushi variation on bi bim bap called hwoedupbap - ribbons of raw salmon, tuna and snapper tossed with tangy chile sauce over shredded lettuce, rice and veggies - would make an ideal summer dish.

But Park does diners no favor by labeling a dish beef teriyaki (think steak, sweet brown Japanese sauce) when it is really bul go ki - a traditional Korean dish of thinly sliced marinated beef cooked with onions. Despite the switcheroo, I would have been happy had the meat not been cold by the time it arrived.

The chicken ramen noodle soup was not what I expected, either, but it was truly delicious - a full-flavored, almost oniony chicken broth enriched with miso, then filled with moist nuggets of chicken and long, chewy noodles that beat hands down the brittle, grocery-store bargain packs. As hearty as the ramen was, the roasted scallion soup was sheer elegance, a clear broth perfumed with heat-speckled green onions and a minty whiff of shiso. At the bottom of its deep blue bowl sat two fried scallops, their tempura crusts soaked through and billowing like puffy clouds.

If Kissen has a sweet spot beyond tempura, it would be its creative maki rolls. The ngiri sushi (individual pieces of fish placed over rice) occasionally lacked craftsmanship, both in the slicing of fish and in rice balls that too easily fell apart. But the composed rolls of maki were, both in their scale - just right for a bite - and their original combinations, spot on. The spicy tuna unagi maki brought the contrast of sweetly glazed eel over the cool sensation of spicy raw tuna. The oddly named "hot dog" maki paired buttery yellowtail with the snap of asparagus. Nikki maki brushed rich king crab against the sour sweet of pickled ume plum. The soft chewiness of cooked yellowtail was tucked inside a rice tube rolled in black tobiko roe, a jacket of tiny black pearls that popped between the teeth.

Even Park's oversized vegetarian "garden" roll was a hit, wrapping a salad bowl's worth of romaine lettuce, cucumber, peppers and carrots into a refreshingly coherent mouthful of produce.

By our meal's end, though, Kissen seemed to have exhausted all of its imagination. I only suspect this because the dessert selection was as follows: green tea ice cream; green tea ice cream wrapped in mochi rice cake; tempura-fried green ice cream.

With a hot cup of postprandial green tea to wash it down, who could ask for more?