The burger: It's hardly rocket science to believe that if you want a great veggie burger, you go to a great vegetarian (or vegetarian-friendly, anyway) restaurant. Someone recently asked where they could go and not end up with a thawed Morningstar Farms patty — that a restaurant would actually have the temerity to serve such a dreary supermarket downer is a mind-boggler, but that's another story — and of course my first thought was the Birchwood Cafe.

I was not disappointed. The restaurant, 20 years young, has had a black bean-based burger on the menu since opening day, and although I'm a frequent diner (don't get me started on my love for the savory waffles, or the vegetable handpies), I've never gone down that particular path.

Not that I feared the burger equivalent a tragic no-food-with-a-face substitute. That has never been the Birchwood's style. And it's not that I didn't know that the restaurant wouldn't approach the veggie burger with the same intent that it displays with the rest of its frequently but not exclusively vegetarian menu.

I was not surprised to learn that chef Marshall Paulsen has, during his eight-year tenure, put the black bean burger through probably two dozen refinements. It's easy to see why the one I scarfed down earlier this week is a pinnacle experience.

First, the thick patty nails the moisture-texture conundrum that trips up so many dry and pallid veggie burgers. Paulsen's secret lies is in the way the beans are prepared. Some are simmered for six hours in highly salted water until they're tender but not mushy, while others are cooked longer, then pureed and seasoned with garlic-infused oil.

Binders include white quinoa, the flesh of dry-roasted russet potatoes, potato starch and locally raised cornmeal, and the mix is seasoned with plenty of cumin, coriander, salt and black pepper. When the B'wood's kitchen was the size of an Eden Prairie McMansion's walk-in closet, the black bean burgers were baked. But thanks to a recent renovation and expansion, Paulsen finally has a kitchen that matches his skills and ambitions, and one benefit is embodied in the way he's now able to prepare his black bean burger. No more baked burgers, thank you very much. That bean-quinoa-potato mixture gets formed into a ball, and as each ball is seared in a hot cast-iron skillet, it gets a schmush, Smashburger-style, and cooked until the outside of the patty develops a pretty decent burger-like char, and the interior remains solid and relatively moist.

For those who think that "veggie burger" is synonymous with "boring," prepare to have your expectations shattered, Birchwood-style. First of all, there's an astonishing level of detail that goes into the (all-organic, naturally) bun, which is baked on the premises each morning. Paulsen calls it a "birdseed" bun, because it's sprinkled with ingredients typically associated with birdseed: flax, millet sunflowers. \

But the bread itself is a far cry from the vacuous, one-note white-bread burger buns that seem to norm, its wheat flour base fortified with barley and molasses. It's no wonder that Paulsen is justifiably proud of it (and if you're a fan of the B'wood's turkey salad sandwich — and if you're not, you should be — it's served on a loaf version of "birdseed" bun). And if you didn't think there was room for improvement, Paulsen finds it, buttering the inside surfaces of each bun giving them a light toast on the kitchen's flap top grill.

From there, Paulsen piles on the flavors, and doesn't hestiate to step outside the burger garnish comfort zone. The combinations change about eight times a year, depending upon what's seasonally available. Right now, it's a cool, crunchy cumin-kissed apple-cabbage slaw, a thin slice of sharp Cheddar, a healthy swipe of honey-jalapeno-mustard mayonnaise and a crown of flavorful microgreens, some sweet, some bitter.

Did I miss my weekly beef burger? Not for a second. The same cannot be said for the vast majority of veggie burgers I encounter.

Price: $12.

Fries: Oh, the fries. One of the many benefits of the Birchwood's recent remake is that the kitchen has the room for a deep fryer. In the old days, Paulsen would occasionally offer fries, but it was a huge hassle. "We would fill a stock pot with oil and use a candy thermometer," he said. "We only had a six-burner stove, and so that would take a burner, and it was so messy."

No longer. The B'wood's much roomier facility also makes space for the time-consuming pre-frying process. Potatoes are sliced, skin-on, then soaked in water overnight ("To get rid of some of the starches, so they're not so sticky," said Paulsen). They're pulled from the water and refrigerated for a day, then blanched in 325 degree rice bran oil (a non-allergen, non-GMO product), then chilled again and then fried to order, this time with the rice bran oil at 400 degrees.

They're pulled from the fryer just as they reach a deep golden brown, then dusted with a fine-grain sea salt, and the results are fantastic. Of course, it helps that Paulsen starts with organic russets sourced from Heartbeet Farm in Zumbro Falls, Minn., and they boast a pronounced root vegetable flavor, a quality often lost on Planet French Fry.

"If you start with good ingredients, you'll have a good outcome, as long you don't screw it up," said Paulsen.

Each order comes with a terrific house-made ketchup, noteworthy for its bright, slightly sweet tomato punch and thick, fries-clinging consistency. It's the result of a lot of experimentation on the part of the B'wood's kitchen crew.

"A lot of people are anti-house ketchup, because the general feeling is that Heinz does it best already," said Paulsen. "So we modeled ours on Heinz, what goes into it, and how it's made, only we use organic tomato paste and organic corn syrup. It's still traditional ketchup, but it is made with better ingredients, and it doesn't have those generic added flavorings."

Along with ketchup, the fries are also served with a second dipping sauce, and the formula changes frequently. Right now it's a delightfully garlicky mayonnaise seasoned with roasted fennel.

Here's a tip that will keep fries-seekers' devastation to a minimum: They're available at dinner only. Right now, lunch is a fries-free zone, and it's strictly a logistical puzzle: How to serve the restaurant's popular breakfast while also going through the prep necessary prep details.

"I'll make sure that it's on my next creative team meeting agenda," said Paulsen. "We'll figure it out."

The price is right. Buy a black bean burger at dinner, and a handful of fries is just an additional buck. Better yet, splurge ($5) on a highly sharable appetizer-size order (again, dinner only). You won't regret it.

Where the chefs eat: When Paulsen craves a (non-Birchwood) burger, he goes to the Nook (formal name: Casper's & Runyon's Shamrocks Irish Nook). "That'll always be my place, I've been going there since I was 12, so that might have something to do with it," he said. "It's the perfect example of the perfect burger. If I go out once a week for a burger, it's going to be at the Nook."

Address book: 3311 E. 25th St., Mpls., 612-722-4474. Open 7 am. to 9 p.m. weedays, 8 a.m. to 9 p.m. weekends.

Talk to me: Do you have a favorite burger? Share the details at rick.nelson@startribune.com.