"If you do it wrong, it's blasphemy," said Mr. Z's owner Mike Zielinski of the Philadelphia cheesesteak.
Zielinski should know. In 27 short years, he's learned a thing or two about people and places - all the while indulging his appetite and passion for food.
He grew up in Northeast Philadelphia, playing stickball in the streets. In the summer, over-heated sweaty little boys would head over to "Mr. Z's" (Zielinski's father's house) for homemade lemonade. It's the recipe Zielinski serves today at his open-air lunch counter on Southard Street under the shadow of the purple Pegasus Hotel.
"On the northside of Philly, American cheese is more popular," he said. "In south Philly, they prefer Cheese Whiz. My dad’s generation preferred provolone. In Philadelphia it's North versus South and young versus old. It's like a religion."
The key to a great Philly cheesesteak, according to Zielinski, is the bread: It can't fall apart and it has to have that particular flavor attributed to how water "up north" tastes. Zielinski is able to have the bread shipped to Key West to offer the goods.
"There's a lot of people in Key West who know this food and they couldn't get it anywhere, so I set out to do it," he said.
The eatery serves many variations of the cheesesteak including the chicken cheesesteak and the pizzasteak.

The men of Mr. Z's are Shlomi, left, Paddy Rooney, owner Mike Zielinski and Garreth Heath. Locals make a beeline for the cheesesteak sandwich and homemade lemonade at the increasingly popular eatery that stays open until 4 a.m. seven nights a week.

The rest of the menu is like a culinary tour of Zielinski’s hometown.
The Italian roast pork sandwich features slow- roasted pork seasoned with sharp provolone and broccoli rabe (a spinach-like vegetable). The sandwich is a tribute to a famous Philly eatery called “Tony Luke’s” "That's where my father and I would eat before or after an Eagles or Philly's game,"
Mr. Z's stromboli is influenced by a Sicilian neighbor. Zielinski remembers his childhood, when his mother and he would roll the stromboli’s in his neighbor’s kitchen. "She believed there was only one way to make it - with capicola ham, pepperoni and mozzarella cheese." This recipe has become a staple of Mr.Z’s, named the “classic Italian stromboli.”
At $12, the stromboli is the most expensive item on the menu but is worth it. Zielinski says, "It's huge…It can easily feed four,” Besides the classic Italian stromboli, Mr. Z's makes a cheesesteak stromboli and a vegetable and four-cheese stromboli.
Also on the menu is a hot roast beef, with melted chunks of sharp provolone cheese, based on another famous Philly staple “Nick’s Roast Beef.”
At Mr. Z's, all the sandwiches are $6 - tax included. It sells pizza slices for $2 and a whole pie for $11.
The pizza, Zielinski said, has gone through a couple of incarnations since the eatery opened. He spent a couple of months refining his recipe for dough. "We make the perfect pizza dough fresh on site," he said, "and the sauce is our own recipe, too. But it's all about the dough."
Zielinski arrived in Key West two years ago, following in the footsteps of an old family friend who is a celebrated chef on Duval. His goal was to finish his second novel. "But I got caught up in working on an independent film but it fell apart and we didn't get the money," he said. "So I turned around and took everything I had to open Mr. Z's."
After a seven-year gig working intelligence for the U.S. Navy, he figured starting his own small business wouldn't be too hard.
"The Navy taught me a lot of things that will be with me my whole life," he said.
Zielinski was stationed in Spain for three years and said he became fascinated with the culture. His impressions became the basis for his first book "Gazpacho" that was published online by Writers Club Press, a subsidiary of Barnes and Noble bookstores.

"The story is based on me and two of my best friends," he said, "three Americans discovering a culture through American eyes. I tried to include every facet of Spanish culture."
Between writing and running the counter, Zielinski has had little time to miss the flavors of Spain like paella, sangria and happy hour "tapas." He is too busy discovering the taste of Key West. "My favorite fish is definitely mahi-mahi," he said. "Down here these restaurants do so many things with it. Places like Antonio's and Alonzo's - the things they do with mahi-mahi are awesome."
But a desire for homemade food, the food a person grew up on, that's a longing it's difficult to overcome
and a reason for Zielinski's success. "I've met so many great people. They come in and tell me how happy
they are to have found this food and that makes it all worth it," he said. "I don't know about getting rich or
opening a chain, but I think the potential for Mr. Z's is there."