ROCKLAND — Roasty's, Portland's roast beef sandwich shop, quietly made an appearance in Main Street Markets' kitchen last week for two days, delighting locals.

It seemed like a random collaboration until the connection was revealed. Co-owner Jenn Rockwell is also the owner of Roasty's, the casual eatery she founded quietly last year.

"We had a very niche, very regionally specific concept of what a roast beef sandwich should be," said Rockwell, "We make sure it's perfectly, consistently cooked every time."

Rockwell said people have an emotional attachment to what the perfect roast beef sandwich is, particularly because so many regions in the U.S. claim theirs is the best.

For that reason, she traveled around the U.S. to taste-test roast beef sandwiches, and the variations are reflected in the menu.

Signature sandwiches are made in the styles of Boston and the North Shore, Buffalo, Chicago, L.A., New Jersey and Philadelphia.

"People have a clear idea of what they want from these regions," she said. "It has to be the right topping, the right bread, the right temperature — rare — the perfect cut, and the perfect au jus, and until recently, you could only get that sandwich if you went to these regions."

Everything on the menu can be augmented with homemade sides and sauces, and, of course, the star, au jus.

"We take all of the trimmings and that gets braised to make a really rich and delicious au jus," she said.

Rockwell said she made the choice to open Roasty's in Portland because there was more volume and better numbers. She lives in Rockland, managing Main Street Markets, while her manager, Sean Williams, handles the Portland shop.

Williams comes up on his days off (Mondays and Tuesdays) to run the Roasty's pop-up in Rockland. Meanwhile, Rockwell travels down several times a month to Portland to handle business details of her shop. 

"Everyone has been curious about the sandwich shop in Portland, wondering what I've been up to," she said. "We've really wanted a way to introduce it to the public in Rockland."

Rockwell said one of the reasons the casual eatery has been so under the radar is that they did a number of pop-ups prior to opening in Portland to get customer feedback.

"There's no sugarcoating an opinion in this state," she said.

"The first week has already been a hit with great feedback and plenty of 'OMG' texts," she said. "We hope to see familiar faces, keep the momentum going, and maybe even explore future pop-ups or a more permanent spot down the line."

The Rockland menu is going to be slightly pared down from the Portland menu.

They're set up inside the Main Street Markets Gallery (adjacent to the market and café at 435 Main Street) every Monday and Tuesday in December from 11 a.m. to 7 p.m., when their Portland shop is closed.

For more info visit: https://www.eatroastys.com/menu

Kay Stephens can be reached at news@penbaypilot.com