You may have heard of retro dishes like lobster Thermidor inspiring modern menus at American restaurants. And, if you've been lucky enough to have such an experience, you may have gone on a journey with a chef through a tasting menu that tells you a story about them, or about a particular place. But you've likely never had a dining experience that, over a couple of hours, attempts to take you time-traveling backward through important moments in global food culture, and forward into a future of dining we can only begin to imagine.

The creativity and ambition of chef Ryan Shelton and his team at Merchant Roots, in San Francisco's Fillmore District, continues to expand and flourish as the restaurant shape-shifts every couple of months with its change of menu. The latest, running through mid-January, is called "Time Traveler," and it's the kind of thought-provoking, theatrical dining experience that you'll want to discuss and remember for days or months after. (Spoiler Alert: If you prefer to be surprised with your multi-course dining experiences, you should probably stop reading here and just book a table.)

The premise, which is set forth with some slightly goofy set pieces in the dining room, along with a video screen and digital time display, is that the menu is going to bounce around in time, telling a story about food and the human creation of it that isn't chronological, but nonetheless makes some narrative sense. The first course hints at some of the whimsy to come, with some snacks inspired by the 1980s: a piece of blackened fish, a deconstructed seven-layer dip that nods to "nouvelle cuisine," and an animal-shaped cheese cracker draped in sprouts meant to be a Chia Pet.

Next, it's on to pre-history, 65,000,023 BC. A baby root vegetable of your choice — each diner chooses a tiny radish, carrot, or turnip — which is served with chicory mousse, a marinated "prehistoric" quail egg, some rye bread "soil," a bag of seeds, and a tiny shovel. You're told that choices you make in these early courses will impact what comes later.

A "hunter and gatherer" course takes you to 30,023 BC, with California native ingredients like a small, well seasoned piece of elk — grilled on a small stove brought to the table — uni, mushroom and berries.

Asian trade along the Silk Road is represented by noodles, duck "thread," ginger cabbage, chili crunch, and vadouvan curry. That's followed by a trip across the ocean and forward 500 years to The Colombian Exchange, when New World ingredients first came to Europe — represented by a dish of clay-baked potatoes, corn tomalito, a green chili sauce, and a cheese fonduta from the Old World.

You then transport to 1953 and get a TV dinner of tuna casserole — an excellent, croquette-like version — potato puree, and peas that are mixed with whatever root vegetable you chose back in pre-history.

The Multiverse is represented by a burger three ways — an ancient Roman meatball called isicia omentata, steak tartare, and a futuristic bite of spherized flavor gels that tastes like a Big Mac with all the condiments.

One of the most theatrical courses represents Ancient Rome and The Salt Road, in 23 AD. Taking the space of a cheese course, before dessert, diners are given a few pickles, some cheese, house-made summer sausage, and some dressed, miniature lettuce leaves. And you are told about how Romans tended to all have dead palates from lead poisoning, and this led to heavily salted and seasoned food. To mimic the experience, you are given a "miracle berry" to chew on — it's a berry native to tropical Africa, commonly found dried at health food stores, that temporarily inhibits your tongue from tasting tart or sour flavors, making everything taste sweet. The effect, if you've never tried one, is fairly astonishing, making a slice of lemon taste sweet as candy, and turning every wine into a dessert wine — and it's certainly one of the more trippy, science-lab-type courses I've ever encountered in a restaurant.

You also learn about garum, the Roman fish sauce that people often carried in a hip flask, and which can be used to make a quick broth with some hot water. This hot broth counteracts the miracle berry, and you can go back to tasting sour again.

The theatrics continue with dessert, which includes a Depression-era slice of Water Pie, and a set piece of custom dishware that includes a motorized fan to "levitate" a caramel-apple flavored, spherical confection.

Shelton says that the "Time Traveler" menu came together over the course of nine months, and his team — which has produced other interactive, whimsical elements for things like a "Mad Hatter's Tea Party" menu — enjoyed the idea of playing with the butterfly effect, and having choose-your-own-adventure moments that effect the dining experience overall.

Other previous menus have been interesting for the challenges they present for the kitchen to overcome — like the "Feast for Mermaids" menu earlier this year, in which all ingredients had to come from the ocean, or "within arm's reach" of the ocean.

But the "Time Traveler" menu, Shelton says, "really seems to bring with it the Heisenberg 'that which you observe, so too you also change' phenomenon." And it's both mind-bending at moments as well as satisfyingly educational, while still being consistently delicious.

"We wanted a bit of legitimate food history to round out the silliness of this menu," Shelton says. "We struggled with this, because it was important to us not to be ethnocentric, in terms of how we follow food culturally." (Shelton says that he still cringes when they serve the edible Chia Pet "and someone in the room who grew up outside of the US says 'what's a Chia Pet?'").

"We ended up deciding the important thing was not to follow the people, but to follow the food, and so we made it about travel/roads/routes — Salt Road, Silk Road, Columbian Exchange," Shelton says. "These were the major routes of diffusion that food and food preservation techniques took to reach a worldwide audience."

I asked if this is, albeit with a higher concept, what The Bear was referring to when the characters talk about a "chaos menu."

"I have been working in fine dining for over 20 years and I have also never heard that term before," Shelton says. "I figured they made it up for the show, but yeah, I guess, in retrospect, given the way this menu came together, that would be a pretty apt description. Normally our menus have a bit of a flow to them as a result of their context, but given the erratic, time-travel vibe we were going for, the courses don't really have much to do with each other."

He adds, "I suppose we were going for more of a Dr. Who episodic feel from course to course with our time travel...  The breadth of ideas we had for this theme was truly massive and we sort of chose the ideas that would add together to... create a complete (if not cohesive) meal."

The next theme, which begins January 31, is "Into the Forest," which will be "an exploration of ingredients found and foraged in nature." "Time Traveler" goes on through January 20. Find reservations here.

Previously: Chef Ryan Shelton Creates Ambitious Menu That Evokes Thackeray's 'Vanity Fair' In Food