It’s 9 a.m. on a Monday, and Alex Peña is in the process of pushing and twisting freshly ground Polish sausage into what will end up being about 1,000 pounds of links.

Behind him, Pat Strey grinds up and mixes the beef trimmings and picnic roast pork that goes into the Polish sausage, stokes the fire for the smoker and preps a fresh batch of custom deer sausage to close out the production window.

These veteran San Antonio sausage makers have worked side-by-side for nearly 30 years, and life for them truly is all about the daily grind.

Mertz Sausage may be the oldest San Antonio business you’ve never heard of. At 89 years old, the business rarely advertises and isn’t carried by most major area grocers.

But when you do get your hands on the sausage, it’s a chance to taste and explore recipes that dive deep into the past. It’s a tasty trip.

Peña and Strey, both 66, are the longtime caretakers and owners of Mertz, a South Side business on Cupples Road that dates back to 1929. The business was started by Henry Mertz, who scribbled a sausage recipe on a piece of cardboard that continues to be used today.

Mertz sold the business to the late Herman Haase around 1940, who ran the business with his late wife Evelyn until 1972. That was when Peña, who married into the family (and later divorced out of it), was given the opportunity to purchase the business for $35,000 after working in the facility for one year.

“I remember Evelyn told Mr. Haase that I wasn’t going to make it,” Peña said. “When I bought the place, I had a payment on my house and a payment on a new vehicle. Any money person would have said that I was in way over my head.”

But he’s been there ever since, using many of the same recipes, techniques and gadgets, such as the original LeFiell brand smoking chamber that dates back to 1929. Peña likes to joke that the business has survived two divorces and an audit from the Internal Revenue Service during his tenure.

By most measures, Mertz is a small-time sausage-making operation, producing about 7,000 pounds of sausage, salami and stick jerky in various forms. Peña said that the “big boys” can routinely do 10,000 pounds in a day.

The 10-pound box of Polish sausage (equal parts beef and pork) that contains about 50 links and is sold for $25.90 is the big seller that Peña said is the primary driver of business. Mertz also makes hundreds of pounds of the Italian sausage and chorizo that’s served in area restaurants.

Mertz products, including the original Polish, jalapeño and garlic-infused sausage, are sold locally in select area Arlan’s Markets, La Fiesta and a few Walmart locations. Or you can get it at the source from 8 a.m. until close most Mondays through Fridays, where the packaged meats are on display upon entry.

It takes on custom sausage-making orders, too, including venison, and there have been some odd requests over the years.

“We made a batch with emu and ostrich meat once,” Strey said. “We mixed it with the beef and the pork, because they wanted to see what worked better. It was nasty, but that’s not my place to judge. I made it as directed.”

In the 1980s and ’90s, Mertz was a bigger operation, with as many as 28 employees working three shifts and delivering 20,000 pounds of sausage all over Texas on a weekly basis. Bigger is traditionally better in business, but Peña found the opposite to be true.

“Our buying power was huge, but we grew tired of it,” Peña said. “Pat and I would get called at all hours of the night, and once you added in all the costs of distribution and so forth, it felt like we were swapping money more than we were making it. We quit trying to play catch-up.”

Mertz now operates as a team of five, including another longtime employee, Rosio Covarrubias, who has been expertly tying the links to the cooking racks for more than 15 years.

The atmosphere is demanding, yet laid-back. All of the sausage making is done in a room that maintains a constant 50-degree temperature. Instead of clocking in and clocking out, Peña has a system where once the work is done for the week, the workers go home and are paid for a full 40 hours, even if they only put in 30 or so. When they work more than 40, he pays overtime.

Strey, who Peña made a co-owner years ago, makes the process look effortless.

“I’ve been here 29 years, and for me, it’s all I’ve done,” said Strey, who has 47 total years of sausage-making experience. “I enjoy doing it, and have always took pride in the product.”

Manny Olivo, who used to run Manny O’s BBQ in Universal City and now operates the Cow Tippin BBQ food truck every Saturday in Schertz, puts the German sausage Mertz produces (only available in store every Thursday) on his menu.

“They make gorgeous, beautiful sausage that always turns out delicious once finished in the pit,” Olivo said. “Pat and Alex have always been great working with me. They kind of operate under the radar, which is great for somebody like me, but more people should know about Mertz.”

Peña said that Mertz is doing well financially, but he wasn’t sure how much longer he and Strey will be able to keep the business going. They are getting older, and Peña wants to spend more time out on his 49-acre St. Hedwig property.

There is no plan of succession for Mertz, but for now, San Antonians can get their hands on true links to the past from two experts of the craft.