The burger: The James Beard Foundation's Blended Burger Project is back for its fifth season, and Book Club chef/co-owner Asher Miller is on it.

"It's always a good thing to be talking about James Beard, right?" he said with a laugh. "Working with the James Beard Foundation, that's an easy decision."

And a delicious one. The project asks chefs to incorporate "finely chopped, umami-rich mushrooms with ground meat in burgers," a strategy that's part of the foundation's efforts to promote sustainability, health and flavor in the nation's food systems. The project is co-sponsored by the Mushroom Council, and nearly 300 restaurants across the country are participating. The mushroom/meat blend has to be at least 25 percent mushrooms.

The project is based on the following factoids: Americans consume 10 billion burgers annually. Replacing 30 percent of the beef in every one of those burgers with mushrooms would be the emissions-reducing equivalent of retiring 2.3 million cars from the nation's roadways. It would also shrink agricultural land demands by enough square miles to cover the state of Maryland.

To engage the public, the foundation turns the project into a contest, asking diners to go online and vote for their favorites. The top 25 vote-getters will be whittled to five finalists; the top five winners will receive $5,000, plus a trip to the James Beard House in New York City in October. Voting ends on July 31st.

Miller's entry? It's scrupulously composed, and fantastic.

"It's a collaboration," he said. "We put our heads together in the kitchen, and tried to focus on balance."

They succeeded. For starters, the burger's finishing touches are spot-on. A basil pesto adds a bright, summery touch, and a balsamic-boosted aioli inserts a welcome acidity. Baby arugula contributes color (ditto the slices of sweet roasted red bell peppers) and a peppery bite, and a slab of creamy Fontina is a happy alternative to the ubiquitous American and Cheddar.

Miller and his crew also have the good taste to buy a first-rate bun from Denny's 5th Avenue Bakery in Bloomington, then lay on the butter before they get a warm, slightly crispy toast.

As for the patty, it's thick, with rough edges and a nicely charred crust. The beef hails from Organic Prairie, a Wisconsin-based cooperative of family farms. It's a rich and flavorful, 80/20 meat/fat blend that's redolent with fat but not greasy.

The mushrooms are portobellos. They're finely chopped, then seasoned with garlic powder, salt and pepper before being blended into the ground beef.

"We chose portobellos because of their meatiness," said Miller. "They hold up really well when they're cooked. Because they have a relatively low moisture content, they don't turn to mush when they're cooked, and they don't give off moisture that leaks into the patty."

The beef/mushroom ratio hovers near the 70/30 neighborhood. The results are noticeably lighter than a 100-percent beef burger, but each flavorful bite has a satisfying earthiness that's anything but annoyingly, vacuously Lite. Which begs the question: why isn't everyone incorporating mushrooms into their burgers?

Price: $13.

Fries: Not included, but the restaurant's excellent hand-cut, double-blanched fries are just a $2 upcharge away. The burger is served with a heaping handful of (terrific) house-fried potato chips.

Find it elsewhere: A few other Twin Cities restaurants are participating in the Blended Burger Project, including the St. Paul outpost of the French Meadow Cafe, the Gold Nugget Tavern & Grille in Minnetonka and Book Club's sibling establishment in northeast Minneapolis, Red Stag Supperclub.

Pre-Father's Day: Consider plying Dad with burgers and wine on the afternoon (noon to 4 p.m.) of Father's Day Eve, aka June 15, when Book Club hosts "Burgers & Rose." "We're going to cordon off the parking lot," said Miller. "We're hoping for two to three hundred people." Expect to encounter four styles of burgers (including, yes, the Blended Burger Project entry, and a vegetarian version made with spinach, ground walnuts and mushrooms), plus several varieties of rose. There will be games (including a wine-spitting contest) and other events. Tickets ($25/person) are available here, or at the door.

Where he burgers: "I used to have to go to the Mall of America for the Shake Shack," said Miller. "But now there's one near Southdale, and that's quite a relief for me."

Address book: 5411 Penn Av. S., Mpls., 612-822-5411. Open 11 a.m. to 10 p.m. Monday through Thursday, 11 a.m. to 11 p.m. Friday, 9 a.m. to 11 p.m. Saturday, 9 a.m. to 10 p.m. Sunday. The restaurant has a small parking lot and a sunny sidewalk patio.

Metro Transit: Routes 4 and 4P.

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