"We have an open kitchen, so we try to show it to them," said Patel, gesturing to the spotless glass pickup window that provides an unimpeded view of chef Arjun Thakur lording over his grill, flat-top and tawa, an enormous, shallow, cast-iron pan so heavy they had to weld handles onto the sides to lug it into position.
If this visual aid still doesn't help, Patel resorts to uttering the B-word: "When I say burrito, they get it."
Flavors and fillings notwithstanding, it's the most apt comparison - a 6- to 7-inch crisped flatbread, stuffed with meats, vegetables, eggs, cheeses and sauces, then twisted up and wrapped in paper. (The Taco Bell chain, which has a handful of locations in India, has introduced a hybrid "kathitto" to its menu over there.)
Kati rolls are well-engineered for both harried office workers, who make up the majority of Spice End's lunch crowds, and post-last-call revelers looking for something quick and filling as a pre-emptive hangover cure. (They serve till 3 a.m. Saturdays and Sundays, and midnight every other night.) Makes sense, as both Patel and his partner, Vaishal Soni, studied engineering.
Patel, 23, and Soni, 26, met in a college calculus class in Central Jersey, when they decided to cram for a final exam together. As it turned out, both their families originated in the state of Gujarat, in India's northwest. And even though both were pursuing degrees in engineering - Patel civil and Soni electrical - both had entrepreneurial brains.
"That's why we clicked," Patel said of his and Soni's shared desire to own and operate an independent business.
In spring 2012, Soni floated the kati-roll idea, and the pair "jumped on it," opening in May of this year.
Soni had managed Indian restaurants in Jersey, and he brought on his former co-worker Thakur, 28 - who's cooked in Dubai and in the galleys of cruise ships - as Spice End's chef.
Then came their exhaustive R&D period.
Deceptively simple, kati rolls are predicated on the quality and consistency of the bread, for which the trio tested multiple flours and recipes before landing on the exact-right wrap. They declined to share the full ingredients for it.
"The flatbread is the most important for us," Thakur said. Thicker than roti but thinner than traditional Indian naan, the rounds are flattened in a press before being browned in oil on the screaming-hot tawa, which is roughly the shape of Captain America's shield.
The texture is superheroic: buttery and crispy on the outside, soft but not overly doughy inside.
Once the bread's ready, Thakur and his cooks get to dressing it. Their biggest seller is chicken tikka, the immensely popular Anglo-Indian dish of white-meat breast chunks in a mildly spiced sauce.
As with the rest of Spice End's rolls, the meat is topped with a generous helping of Thakur's homemade mint-coriander chutney, sliced raw red onion and a sprinkle of chaat masala, the chef's personal powdered spice blend.
"Uncountable spices. I cannot count that high," claimed a smirking Thakur when asked how many spices make up his masala, though we have a feeling he's more than familiar with the exact number.
Aside from chicken, also available with fluffy scrambled eggs or doused in a tangy achari pickle sauce, Spice End roll fillings include shredded lamb, cheese, potato and spiced mixed vegetables (green beans, peas, carrots, tomatoes).
Beef, too - one meat you're not going to find in many Indian restaurants, given Hindu dietary proclivities.
Patel and Soni didn't run into any opposition from family and friends when they floated the idea of serving it. "While not so many Indian people eat it, a large percentage of other people do - they love beef," figured Patel, sounding like a proper entrepreneur.
"We wanted to keep the menu as simple as possible, not a three-page menu where we can't even focus on one thing," Soni said of Spice End's selections, which extend past rolls to include rice platters, house-blended mango lassis and unmistakable Indian glass-bottle sodas like Thums Up and Limca.
And those secret sauces
Asking about the components of the restaurant's signature squeeze-bottle sauces - one a fire-engine-red, chili-based hot sauce that some compare to sriracha; the other a mayo-and-yogurt white sauce that some compare to ranch - results in more good-natured stonewalling from the owners.
The Spice Enders play pretty much everything close to the vest, but they're candid about the fact that theirs is quality fast food - emphasis on the fast.
Indian food, with its complex spicing and one-thing-at-a-time cooking processes, often takes forever to prepare correctly. Whether this kati-roll-obsessed team is cranking through a lunch rush of hungry starched-shirt financiers or wrangling a glut of drunken paneer cravers past 2 a.m., speed is as big a concern as quality.
"Make it fresh and sell it fresh - that's the biggest challenge for us," said Thakur, who calls Spice End's kitchen the busiest he's ever worked in.
"It has to go out fast," said Patel, "or we're not doing anything right."
Drew Lazor has been writing about the local food scene since 2005. His twice-monthly column focuses on unexpected people doing unexpected things in Philadelphia food. If you come across a chef, restaurant, dish or food-related topic that bears investigation, contact him at firstname.lastname@example.org or on Twitter @drewlazor.