Taking a seat inside the Hi-Lo Diner is an instant mood-enhancer.

Heck, just driving past this gleaming, painstakingly restored structure — which started life in a New Jersey factory in the late 1950s and arrived in Minneapolis last fall, split down the middle and strapped to a pair of flatbed trucks — is enough to trigger a rush of endorphins.

If you’ve ever wondered what fast food looked like before McDonald’s ran roughshod over the American landscape, the hash-slinging Hi-Lo is a good place to start. And for those questioning the diner’s historic bona fides, just slip into one of the booth’s tight-ish quarters. Yes, American waistlines were smaller in the pre-Big Mac era.

An admirable facet of chef Heidi Marsh’s cooking is that she’s not aiming for some kind of arch, postmodernist statement on diner fare.

Instead, she gives a great big bear hug to the American short-order universe. Even better? Her starting point is etched with the words “from scratch.” “Nothing comes out of a box,” she said. “I save that for camping.”

That take-no-shortcuts approach starts with pancakes. Such terrific pancakes. Marsh’s chemist approach — buttermilk for tenderness, a bit of egg white for volume, baking powder and baking soda for height — yields a just-right specimen: browned, plate-sized and not-too puffed-up, yet not crepe-like, either. (They also pique my curiosity: How would Marsh handle a waffle? Beautifully, I imagine.)

A slight hint of lemon zest adds a perky finishing touch. At least until the pancake’s heat begins to liquefy a generous dollop of butter, and it’s time to reach for that pitcher of thick, sweet, Wisconsin-made maple syrup.

It’s become a favorite breakfast of mine: A $3 Heidi Marsh pancake, with a $2 side of two creamy, fluffy scrambled eggs. It’s hard not to see the similarities between McDonald’s, in terms of speed (nearly as fast) and price. Yet the quality is exponentially higher and, as an added bonus, you’re seated in a sun-soaked, museum-quality 1950s diner. How great is that?

The big-portion breakfasts, served all day, are definitely among the kitchen’s strengths. The Benedict is spot-on, with slabs of smoky, thick-cut ham draped over toasted English muffins, then topped with poached eggs — the whites firm, the yolks runny — and silky hollandaise. The final flourish is a happy one: spears of cooked-just-right asparagus.

The $11 price tag is more than reasonable. “I want people to get their money’s worth,” said Marsh. Obviously.

The smoked salmon version? Just as impressive. Ditto the omelet, overflowing with rich Gruyère and a kitchen garden’s array of fresh herbs. The over-the-top corned beef hash hits all the requisite notes, and French toast aficionados will enjoy Marsh’s decadent, lavender-scented version.

Deep-fried delight

A snazzy diner calls out for a snazzy signature item, and Marsh is up to the task. She’s christened her creation the “Hi-Top,” and to say that each iteration is worthy of a berth at the Minnesota State Fair is an understatement.

Here’s the premise: start with a yeast-based raised doughnut. Instead of round, make it square, and fill in the hole. Give it a simple, not-too-sugary glaze and then use it as a foundation for all kinds of excursions into unadulterated dietary excess.

Why not stack fried chicken on a doughnut, and smother it in gravy? Especially when the results are this tasty, and loaded with contrasts: the meat so juicy and teasingly feisty (thanks to a jalapeño/garlic brine), the skin so palpably crunchy from a corn-flake coating. It should be served with a Lipitor.

Similarly amusing — and satisfying — is a towering pile of short ribs, the meat fall-apart tender and swimming in a sweet-hot Korean-inspired glaze. The whole thing was topped with a slaw that’s crunched-up with tart Fuji apples and finished with a naughty, bacon-fat-enriched dressing.

Marsh covers a bunch of bases, and by the time I’d sampled my way through iterations involving pulled pork, a riff on the BLT and even a modified lobster roll, I couldn’t help but wonder how these sharp ideas would play out on a savory biscuit rather than a dessert-ey doughnut.

They do, however, raise no hesitations when in sweet-treats mode, whether they’re unapologetically buried under baked apples and drizzled with a salty caramel sauce, or filled with glossy vanilla pastry cream and splashed with chocolate sauce.

Staying true to the diner genre, there’s pie. Baker Mary Vorndran is well versed in the pie-making arts, and she offers up a half-dozen varieties that cover the gamut, from streusel-topped mixed berry to a chocolate/peanut-butter monster buried under whipped cream.

Vorndran’s buttery crusts tiptoe the fine line between sturdy and flaky, and she has a deft way with fillings. The peak experience is the lemon meringue, with its teasingly tart custard crowned by lavish swirls of airy meringue. It’s perfect, and here’s hoping it never comes off the menu.

A winning cheeseburger

When it comes to the burger, Marsh doesn’t kid around. It’s a double-patty knockout, a prime grind of short rib, chuck and brisket with some beef fat (and a splash of mustard) elbowed in for good measure.

It gets the Big Mac treatment — pickles, American cheese, a tangy sauce — and it arrives on a beauty of a bun baked at nearby Turtle Bread Co., along with a generous handful of lightly seasoned crinkle fries, one of the few dishes not prepared on the premises.

Other highlights? Fish and chip fans will enjoy Marsh’s take, which involves fresh cod (“I didn’t want to just pull something out of the freezer,” she said) and a delicate, beer-fueled tempura batter.

The cod trimmings end up in hearty bacon-sweet potato chowder that’s definitely worth ordering. And it’s easy to appreciate Marsh’s attention to detail. Peers working in quick-service environments might not bother with dolling up a side salad, or spinning milkshakes by hand, but that’s not the way it works in the Hi-Lo kitchen.

“I just like to keep things approachable,” said Marsh. “Not to overuse that word. But I want to make food that people can relate to, without overdoing it.”

Full marks on that score. As for the flops, an otherwise noteworthy open-faced turkey sandwich was marred by a gravy so salty it rendered the meal inedible. A Reuben was more bread than beef, and it was boring, which is one adjective that should never be associated with that classic sandwich. And here’s the weird thing about that deep-fried cod: Although it tastes as pristine as can be, its aroma, which perfumes the dining room, can be decidedly fishy. Go figure. And where are the diner classics, like liver and onions, or a tuna salad sandwich?

Along with hiring Marsh, co-owners Mike Smith and James Brown (they’re also the proprietors of Forage Modern Workshop, across the street) have made all kinds of smart decisions, not the least of which was partnering with Blue Door Pub co-owners Jeremy Woerner and Pat McDonough to run the operation.

Cheers to their ingenious notion of dropping a historic diner on a beat-up corner. It’s a great origins story: A Cleveland collector pulled the structure, with its shiny, last-gasps-of-art-deco curves, off the foundations of its longtime home outside Pittsburgh. Brown discovered this treasure on the internet (where else?) and after it arrived in two pieces — portability was a built-in design feature — it was attached to its new kitchen, which was fashioned from an abandoned Taco Bell franchise, surely the best-ever re-use of that benighted building type.

After ensuring that the diner’s every nook and cranny sparkled — while discreetly updating its lighting and other mechanical systems to 2016 standards — Brown and Smith improved upon an already good thing by adding a roomy patio out back.

They also had the good sense and discernment to commission Paul Shively of Up & Onward of Minneapolis to design the Hi-Lo’s carnival-worthy neon rooftop sign, and then tap Bloomington-based Archetype to build and install it. Who needs to advertise, when you’ve got such Instagram click-bait glowing above the front door?

In case anyone was wondering, this is how historic preservation is done, by exhibiting a healthy respect for the past while making allowances for contemporary needs. And here’s a lesson for restaurateurs everywhere: Design does indeed matter.