After a recent dinner for two at Cyrus, the Michelin two-star restaurant in Healdsburg, the server presented me a bill for $454, before tax and tip. That was for two tasting menus (one with a wine pairing), a preprandial half-ounce of Uruguayan caviar partnered with a splash of Champagne and a rhubarb soda pop.

Following dinner for four last month at the Healdsburg Bar & Grill, the new bistro opened by the owners of Cyrus just two blocks from their flagship restaurant, I walked away with a tab totaling $109.05. Our meal included four entrées, three add-on side dishes, an entire pizza, four cocktails, tax and 20 percent gratuity.

Which did I like better? Well, caviar and Champagne do, as they say, turn a girl's head. Yet it turns out that Cyrus chef and co-owner Douglas Keane knows his way around a hamburger just as deftly as he does around Wagyu with foie gras. While I wouldn't have guessed the barebones HBG as a Cyrus pedigree unless I'd been told, it's darn good.

After HBG debuted in April, it caused an instant stir. How could it not? When the original Healdsburg Bar & Grill opened in the summer of 2001, it was as a counter-service pub. It evolved into a full-service restaurant with an enormous menu, but by the time Keane and Cyrus co-owner Nick Peyton took over operations, it had devolved into a very tired, very beat-up bar ("Oh my God," I heard from a neighboring table at the new HBG one night, "it wasn't just a beer joint, it had such a beer-joint smell!").

And now, the restaurateurs who landed a two-star Michelin rating plus a James Beard Award nomination have stepped in with a short but pithy menu of burgers, pizzas, three sandwiches, a couple of appetizers and french fries. No reservations are taken except for parties of 10 and over, and in its first week, HBG served 565 people a day, parked in just 70 seats in the dining room and 70 seats on the patio. The tiny kitchen cranks out more than 200 pizzas each shift, hand-pulling fresh dough while endless rows of burger patties sizzle on a flat grill, cooked, as Keane dictates, to a red-centered medium.

It's a clever concept. If guests at Cyrus might periodically experience sticker shock ($63 for a half-ounce of Black River caviar), guests at HBG can feel sticker euphoria, at just $7.75 for a half-pound, freshly ground Meyer natural Angus beef burger topped with handcrafted Alexander Valley pickles and roasted garlic mayonnaise on a Costeaux Bakery sourdough bun. It's easy to get generous with the add-ons, like the Hobbs' Applewood smoked bacon ($1.75), Haas avocado ($1.25), sautéed mushrooms ($1) or Rogue Creamery blue cheese ($1.50). I did, and my bacon-mushroom, Vella jalapeño Jack burger billed out at $11.50.

Then, there are the sides, such as $2.25–$3.50 for variously flavored french fries, or $7 for a field green salad dressed in citrus DaVero olive oil vinaigrette. Add in a mandatory cocktail like the compelling Dark and Stormy ($8), a mixture of dark rum, Cock'n Bull Ginger Beer and a squeeze of lime, and it's clear this isn't exactly a McDonald's value meal.

Thus, I suppose, the small shriek from one nearby guest at lunch on the patio one afternoon: "Fifty dollars? How the hell did we do that?"

Still, it's impossible not to want to come here often and order a lot. Former Cyrus line cook John Hallgrimson mans the kitchen, sending out the best burgers I've had in recent memory. Juicy doesn't describe it well enough, and there's an appealing herbal quality to the meat, the patty gloriously charred on the edges. The sandwich is so big it deconstructs itself, collapsing with red onions, iceberg lettuce, a pickle spear, bread and butter pickles, and an ocean of juices running into the toasted bun until I give up and just attack it with a knife and fork.

Fries are a must. They're superbly thin, skin-on specimens overflowing from a metal bucket ($2.25, regular), and the spuds get buttery as they cool. Dunk 'em in Heinz or, more interestingly, sriracha, or, for 50 cents a sauce, in chipotle aioli, creamy horseradish, blue cheese or roasted garlic mayo. The fresh garlic-studded models are good, but the fries dusted in parmigiano-reggiano and spritzed with the barest essence of truffle oil are divine ($5).

A bowl of "very adult" mac and cheese is a satisfying side, too, thoroughly rich with Fiscalini Farms raw milk cheddar, parmigiano-reggiano and Hobb's bacon. It's $10, but more than enough for two.

And when Keane is able to harvest his secret weapon—the expansive patio is decorated with wine-barrel planters brimming with tomato vines that as of my last visit weren't quite ripe—he'll add picked-to-order tomatoes, still warm from the sun and offered until they run out.

Meanwhile, there's the homemade tomato sauce lavished on the pizzas. The purée is mild, slightly sweet like red bell pepper, and bright with the licorice-clove tones of fresh torn basil. Those two ingredients plus silky fresh mozzarella are all that's needed on one pristine pie ($10), atop a thin, brittle crust. Another pie is heartier, laden with pepperoni, sausage, bacon, sauce, mozzarella and parmigiano ($14). A third boutique combo hints of its Cyrus heritage, combining a chewy-creamy-tart-sweet-peppery-earthy array of Redwood Hill goat cheese, arugula, caramelized onions and portobello ($12).

If one must have a veggie sandwich in a burger palace, chef Hallgrimson makes the diversion worthwhile. This crunchy-tender model ($8.75) packs in a lot of savory heft, layering roasted portobello, red peppers, cucumber, goat cheese, shaved fennel and garlic aioli. And if one must have chicken, this a very good way to do it, biting into madly juicy and crisp-skinned Fulton Valley Farms organic breast mantled with roasted Anaheim chile, melted Vella jalapeño Jack and wickedly spicy chipotle aioli ($8.75).

On one visit, seared tombo tuna showed up as loin ($15.50), glazed in ponzu and topped with roasted shiitake, an Asian slaw of fuschia pickled cabbage, hot-sweet shaved ginger, radish sprouts and a slick of sesame aioli. Another time, the fish was albacore ($13.50), skewered on pita with sesame-roasted shiitake, Asian slaw, pickled ginger, field greens and wasabi aioli. For both, the portions were disappointingly smallish, but the flavors big, and they came with garden salad to fill in some of the belly gaps.

"Enormous" best describes desserts, designed for sharing (with a football team). But they're tasty enough to scrape the dishes even as a solo diner: A recent visit offered butterscotch pudding ($5.50), HBG brownie surprise ($7.50) and a warm rhubarb crisp ($7.50), thought desserts do change.

If there's any downside to HBG, it's that it can get pretty loud in the dining room and crowded bar, the bartender reflected in an enormous mirror as he crafts Maker's Mark negronis with Campari, sweet vermouth ($9) or the Healdsburg mascot of Belvedere vodka, grapefruit juice, lime ($10). Servers can be brusque. Waits for a table can require patience, and the indoor space is tight; there are no private conversations here. There's more stretching on the patio, seated under bright red umbrellas or grabbing a game of bocce.

Then again, it's hard to nitpick when a chef of Keane's caliber accommodates even kids. A menu doubling as a coloring sheet offers crispy chicken wings with fries ($5), cheese and tomato sauce pizza ($6) and macaroni with butter sauce and Parmesan ($6.50).

And did I mention that dinner isn't $454?

Healdsburg Bar & Grill, 245 Healdsburg Ave., Healdsburg. Open for lunch and dinner, Sunday through Thursday until 11pm; Friday–Saturday to 1am. 707.433.3333.

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