Chef Jeffrey Kim serves simple sashimi bowls with explosively delicate flavors. by Andrea Damewood Jeffrey Kim’s sashimi bowls are perhaps the least flashy in town—but for good reason. The lunchtime bowls at his Aji Fish Butcher y are composed of sliced, dry-aged sashimi topped with only maldon flake salt, simply dressed salad greens, and white rice. That’s it. And that’s all it needs to be. Thanks to dry aging—a relatively new and rare technique—a bite of New Zealand king salmon aged for 21 days, or a 10-day aged McFarland Springs trout tastes achingly tender and packs a concentrated flavor that is far from fishy.  “I don’t want to adulterate the fish,” Kim says. “I want it to shine for what it is, and let the fish do the talking.” New Zealand king salmon bowl Photo Suzette Smith Trout liver mousse pate in retail jar. Trout liver pate mousse toast, topped with greens and plated with dry-aged smoked salmon sausages. Photo Suzette Smith Aji (which means both flavor and horse mackerel in Japanese) is Kim’s passion project. He’s also the head chef of Zilla Sake on Northeast Alberta Street, where he holds a lunchtime Aji pop-up Wednesdays through Fridays. Multiple bowls rotate based on which fish are in season, along with a killer trout pate mousse toast to eat on site. Also, peep the to-go case and grab dry aged fish for home. Dry-aging a fish, Kim admits, can sound a bit dodgy when most seafood is touted for its freshness. But he argues that an expertly-aged fish swims circles around a fresh catch in terms of flavor and tenderness.  “Aging fish has always been a part of sushi,” says Kim, who notes that chefs will age fish over ice, dipped in beeswax, or with salt. “The dry aging process is relatively new for fish.” Kim says he loves seeing how aging different fish results in different tasting notes. After 14 days, sea bream takes on a kelp flavor, he says. For salmon, 21 days is perfect for sashimi, but he’d age it for 35 days if someone wanted to cook it whole over the fire. A former chef de cuisine at Bamboo Sushi, Kim didn't start experimenting with dry-aging until he joined Zilla, and the restaurant and sake house closed at the start of the pandemic. Two years later, he turned it into a retail market. His method is to take whole fish and age it at a specific set temperature and humidity, allowing moisture to dissipate and enzymes to break down. A deli case of in season dry-aged fish. Photo Suzette Smith A panko-breaded and fried katsu bowl. Photo Suzette Smith “People ask: ‘What does that mean, is it jerky then? How do I cook it?” Kim says. “It’s the same thing if you go to a steakhouse; you’re going to see the dry-aged porterhouse and ribeye cost more because there’s a lot of time and care that goes into the meat you enjoy.” The prices for Aji's retail fish are higher than your usual market price, but not by that much. The Glory Bay salmon aged for 21 days is $43 a pound; a similar New Zealand fillet runs $36 per pound at New Seasons. I bought nine ounces to make at home sashimi bowls; we split it and wound up stuffed, which would never normally be the case. Having lunch in house is a great way to sample the way Kim plays with different species. A 14-day aged dry madai (AKA sea bream), was light, clean, and subtly sweet, but had a satisfying bite to the texture. A 10-day aged kurodai (black sea bream), got the katsu treatment: panko breaded and fried for a heartier bowl. Like it is at Zilla, the whole menu at Aji is gluten free. There are a few places in Portland that dry age fish for restaurant use—Chef/Owner Peter Cho dry ages kanpachi at Jeju, for example. But Kim says he’s the only one certified to sell it retail by the Oregon Department of Agriculture. Raw fish is only available via Aji’s website or in store, but the trout pate and salmon sausages can also be found at Providore Fine Foods. “It takes great fish and takes it to the next level,” he says.  Aji Fish Butchery, 1806 NE Alberta (inside Zilla Sake), Wed-Fri, 11 am-3 pm, pre-order pickup Sat 2 pm-5 pm, ajipdx.com ...read more read less