A conversation with Karl Poechlauer of Substance Diner

Off the eatin' path

It’s a strange obsession. Seeking out plant-based comfort food that doesn’t insult me is nearly a full-time job. I am an omnivore but eating so many burgers, birria tacos and barbecue leads me in the direction of trying to eat vegan on the off hours.

Luckily, there is a food truck that is heavy on vegan and vegetarian fare, and far from insulting, flavor, ingredient, and execution-wise, parked permanently in front of one of my favorite breweries, MotoSonora Brewing Company.
Substance Diner, located at 1015 S. Park Ave., is owned and operated by a man named Karl Poechlaur and what he does with non-meat items, making them taste like full-on meat items, is incredible. As usual, I ordered the house burger, the Substance Burger, and as I waited I asked Poechlaur to tell me his life story.

“I am from Washington State,” said Poechlaur. “I moved to Tucson in 2014 to work as an archivist for the National Park Service.”

Spicy Fricken Sandwich at Substance Diner

“After five years, I had lost interest in my job and decided to try to start my own business,” he said. “I had worked as a cook in a lot of restaurants throughout college and graduate school and figured I could use that experience to my advantage with some kind of a food or beverage truck. I invested everything I had saved into building a unique mobile food vending trailer to suit a variety of menus, initially planning to serve coffee and espresso and then shifting into primarily serving food, adapting over time and finding a business model that was sustainable. I took advice and inspiration from other local food truck entrepreneurs and started partnering with breweries and other local watering holes, while also doing events and markets.”

Takeout window at Substance Diner

“The concept started with the design of the trailer, which is based on a vintage 1961 Shasta camper, so it’s from an era associated with the roadside diner serving coffee and breakfast and sandwiches, etc. Places like Denny’s and IHOP have now corporatized what used to be a common and popular restaurant concept usually run by small independent mom-and-pop types. By building out a vintage trailer I was trying to create a food truck with that nostalgic, mid-Century aesthetic, and a style of food to match. I started with a more typical diner menu that included breakfast items, eggs and bacon, pancakes, coffee, espresso, etc. But having been a vegetarian since I was a teenager, I wanted to have plenty of vegetarian options that weren’t usually vegetarian elsewhere, like a vegan burger in place of a beef burger, dairy-free milkshakes, and some of my own creations inspired by classic diner-fare.”

“The vegan and vegetarian options, which actually dominated the menu, eventually became the items that I found people returning to the food truck to get again and again. When the so-called ‘lockdown’ occurred in 2020, my routine of parking at a rotating selection of partnering local businesses, mostly breweries and tap and bottle beer-bar type establishments, was suddenly untenable as places temporarily closed. I set up at the El-Pais Motel and did my best to stay open. Vegan customers really saved the business when they came out to pick up some to-go meals. It was not a lot but I was thus able to stay on life-support, so to speak. After that, I found a brewery interested in a full-time food truck and they didn’t mind that my menu was mostly vegetarian. After about a year at MotoSonora, I felt that the business was stable enough to take a risk and drop a couple of meat and dairy items from the menu and see if it could survive serving a fully vegan menu. There were not a lot of complaints and the business is still alive, so that is the concept now: a vegan vintage diner.”

When the burger arrived I thanked him for the story and, after biting into that burger, I thanked him again for an amazing product I felt less guilty about consuming. It is so delicious, towering, and mercifully messy as well.

Halfway through, I knew I needed more. So, I ordered up his Sonoran Hot Dog. Yeah, let’s see if he can pull that one off. This got me wondering how Substance Diner has been embraced by the veggies and the meaties of southern Arizona alike.

“It’s a very difficult job and I’m lucky to have found a couple of people that are even willing to try it,” said Poechlaur. “Most people don’t understand what a challenge it is, and we all bear the brunt of customers’ misplaced expectations. One or even two incredible workers cannot provide the level of service that a fully staffed restaurant can, with the limited amount of space in a food truck, yet there exists the expectation of fast-food and full-service typically provided by a team of 10or more people and a massive commercial kitchen. And we sometimes attempt to serve just as many people in a shorter amount of time. Everything at Substance Diner is prepared fresh, to order, from scratch essentially. You just can’t make a good hot sandwich that stays good for very long; warm-held French fries lose their crispiness, etc. I’m not ready to give up and go full soup kitchen, though it is tempting. The vast majority of customers are very kind and understanding and patient and I really appreciate that.”

Sonoran Dog at Substance Diner

The hot dog arrived and I tucked in with absolute aplomb. Just like the burger, it astounds beyond the bounds of culinary wizardry. Packed with all of the goodness we expect from a proper Sonoran dog, I ate in wonder and continued to do so even though I was getting fantastically full.

But I had to press on.

Knowing that my wife would want to try his Kale Caesar Salad, I ordered that to go. It was the beginning of Oktoberfest, the brewery was starting to fill up, and folks were beginning to queue up for Poechlaur’s food. I assured them that they would not be disappointed and the meat will not be missed.

“Oh, we’ve been here before,” said a lady with her blonde hair braided in the manner of an Oktoberfest barmaid. “We drive almost an hour to get stuff from Substance. It’s the best.”

After grabbing the Caesar salad, I thanked Poechlaur and asked if he had any last words before I took off.

He did.

“I would like to thank my customers sincerely for continuing to patronize my food truck and would like them to know that I appreciate feedback,” he said as he begins taking orders. “I am always open to communicating with them about their experience with Substance Diner and about ways that I can make it better. I try really hard to provide a good product and good service and if anyone receives anything less, that is something I would like brought to my attention.”

Kale Caesar Salad at Substance Diner

When I got home, I handed my wife the Kale Caesar Salad and she dove right in. She then admitted that it was the best Caesar salad she has had in a very long time. I took a bite and agreed.

Sure, I was still really full, but there is always a little room left for some Substance Diner magic. All Karl Poechlauer needs now is a wand along with a dark cloak adorned with stars and moons. But I don’t really think that’s his style.

Or is it?

Substance Diner can be found at MotoSonora Brewing Company, 1015 S. Park Ave., and is open 5 – 9 p.m. on Monday – Thursday, noon – 9 p.m. on Friday – Saturday, and noon – 8 p.m. on Sunday. For more information, visit substancediner.com and follow Substance Diner on Facebook and Instagram

It was a Sonoran hot dog that made Mark switch from music journalism to food writing when he moved to Tucson from San Francisco in 2006. He hasn’t been the same since.

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