On a hot day soon after Pine Street Market’s spring opening, a line outside snakes around the block: a mass of kids and grown-ups, melting on the sidewalk, waiting to enter the downtown alterna-food court. Inside, the sleek, retro-style Wiz Bang Bar, with its wafer-cone wall patterns and pay-station beacon bearing a signature soft-serve icon, runs smoothly despite the mob. Within just 500 square feet, staffers whip up concoctions like a sundae with fresh berries and grits, everything and everyone as cool as the streamlined design suggests, and the line moves fast.

Yes, those sundaes are a flavor bomb, and the reputation of Salt & Straw, the Portland-based ice cream sensation behind Wiz Bang, guarantees a line for smoked Oregon ham–flavored soft serve and such. But the reason the tiny and jammed ice cream bar works so well (instead of degenerating into chaos) and looks so good? That’s all Andee Hess.

“Function informs the form,” Hess says. The 37-year-old North Portland native—really: she was born inside a house at the intersection of Albina and Alberta—is the city’s rising design star, her company Osmose Design responsible for some of our new landmark spaces. The deco geometry of House Spirits’ Central Eastside tasting room landed her in Wallpaper. The lush elegance of Ava Gene’s dining room, tea-colored custom details at Miami’s Small Tea café—Osmose tailors a project to the individual client, which gives each a distinct heartbeat.

“I don’t want you to walk into a project and be like, ‘Oh, this is Osmose,’” Hess says. “I want you to experience it and ask, ‘Who did this?’”

Still, the Hess sensibility is recognizably clean and creative, roughened up just enough by her affinity for custom details, which Hess crafts to an exacting degree. She says she grew up “always building stuff with my hands.” She attended Portland Community College and Marylhurst to study interior design, then needed an internship. “One of the founders of the architecture firm Skylab went to Marylhurst, so I stalked her,” Hess says. “I was like, ‘It has to be at Skylab.’ It’s an architecture firm, but their focus was on doing full build-out, integrated environments. They had a spec house in Dwell back then.”

Her first project as an intern was the Doug Fir Lounge—she was, she recalls with pride, the person who hung the pleasingly old-school silver bead curtain that still adorns the South Bar. Four years later, after having gone from intern to the head of interior design at the company, she was ready to strike out on her own. “One of my first clients was Patrick Fisher, who owns Hive Modern. He bought a house and asked, ‘Can you do this?’ And I was like, ‘I think I can. I can quit and do this, and I can always get a real job.’”

That was 2008, when Andee Hess Design—soon to be renamed Osmose Design—was born. (“And then there was 2009,” she says, her grimace evoking the tanking economy, a decline she survived, in part, by remaining a one-woman operation.) Today, the company has grown, at its own deliberate pace, to four—“three of us at the core”—and Hess is determined to stop it there. “One of my biggest challenges and goals has actually been to stay small,” she says. “I don’t want to run a business to be a manager of people. I want to run a business to explore and do the projects that I do and know the people and have the adventure. That’s why I’m doing it.”

What Hess is doing is putting Portland design on the national map, with recent projects in New York (Stumptown), Los Angeles (Salt & Straw), and Miami (Small Tea), as well as commercial and residential successes in her hometown. Her particular combination of girl-next-door approachability and whip-smart creativity make it easy to see why clients—particularly, of late, in the food-and-drink world—have been so enamored by her ability to translate their vision into striking spaces.

Kim Malek, Salt & Straw’s CEO, is a major Hess fan. “There wasn’t one single decision she made that wasn’t rooted in some kind of idea about who we are and what we’re about and what we wanted to be,” she says of Hess’s work on the company’s ever-packed SE Division Street outpost. “Our light fixtures are hand-carved to look like little scoops of ice cream made out of wood. We have custom wallpaper made out of tiny panels to look like our waffle cones.” Malek was so impressed with Hess’s work at the Division location that she hired Osmose for her LA stores, too. “When we opened on Abbot Kinney in the Venice area, she worked with a local stained–glass artist who’s been on that street for decades to do custom pieces that are installed on the outside and inside of our shop. People were stopping and taking pictures before that store even opened. She’s really great at adapting our design to reflect the local community and artisans and artists.”

Hess is racking up happy clients as well as a slew of awards. She’s already pocketed three Interior Design of the Year merit awards, and this year made the trade journal design:retail’s prestigious 40 Under 40 list. “Her design mind is responsible for some of the hottest restaurants and food retailers in Portland, Los Angeles, Miami, and New York,” says executive editor Alison Embrey Medina.

For that honor, she represented, Portland style. “People had their whole offices there, and I was like, ‘Oh, this is a big deal,’” she says, recalling the ceremony in New York City. “I was a little late, and I was underdressed. I was wearing flats!”

Now she’s set her sights on something new. “Luxury retail,” she says with a grin. “I especially like saying ‘luxury retail’ in Portland because people freak out about the word luxury, which I think is hilarious. Anything that I can get involved with that challenges me and scares me a little bit, they’re the projects that I like. So anything with the word luxury—how do you chew on that as a Portlander?”