A sourdough starter’s journey from a Somerville kitchen to some of the city’s best restaurants

Loaves of sourdough bread at Puritan & Company.
Loaves of sourdough bread at Puritan & Company.

A bite of Brian Mercury’s sourdough is a taste of tradition that started in a humble Somerville kitchen and has held residency in some of the best restaurants in town.

Speaking with the pastry chef, it’s clear he has an understanding of the rules and history of his craft, but also an appetite for experimenting. That appetite is what led him to create his own mother — a fermentation starter used in bread making.

Mercury, who was recently named Puritan & Company’s pastry chef, has a sourdough starter he’s been using since he created it for a James Beard dinner in 2014, and he’s taken her with him from his apartment in Somerville to Harvest, Oak + Rowan, and now at Puritan & Company.


“I was working with a friend and I was just goofing around and testing out sourdough, starting one with rye flour and one with whole wheat flour and one with all-purpose flour, and just kind of chronologically going through and documenting how everything works,” Mercury explains about the early development of the starter.

What got the ball rolling on using the starter was a dinner at the James Beard House in New York City hosted by Harvest, and former head chef Mary Dumont. “Mary and I had kind of talked about what we were thinking about doing, and I wanted to do bread for the table.”

The starter made the trip to New York City, and Mercury took care to keep her fed and happy. “We drove down, I brought it, and it stayed at the hotel with me. I fed it that night before we went out to dinner, and then brought it the next morning and made the dough.”

The starter lived on and since they were feeding her anyway, Mercury added rolls made from the starter to the Harvest menu, he explains, “I just had her, and we weren’t really doing anything with it, so we would just feed her every day and I just kept her alive, and then eventually we added it to the bread basket. We started with little sourdough rolls so that we could . . . so we weren’t just feeding her for no reason. We were actually using it and doing something with it.”


The award-winning pastry chef left Harvest in the summer of 2016 to cross the river and open Oak + Rowan with Nancy Batista-Caswell — and the starter, which has a name, “Her name is Siouxsie, like with an X, like Siouxsie and the Banshees,” came with Mercury.

But before the restaurant opened, the pastry chef took a detour to San Francisco, where he spent time at the well-regarded Manresa Bread and Quince Restaurants, learning more about his craft. “When I went to culinary school, I learned how to bake bread, and we learned about sourdough, but this kind of modern era of sourdough has changed. It’s really grown. Not that it wasn’t an art form before, but it’s definitely become this kind of like movement.”

Siouxsie the starter took bigger role at the Fort Point hotspot: “We wanted to do sourdough, and we wanted to do our own bread for the table and make it really nice and do the whole process of making all our own butter, all the spreads and stuff, we made everything. We cultured our butter. We did everything for it.”


Mercury admits he didn’t expect this to become a whole flavor adventure. His original goals were strictly practical. “When I first started, I just wanted to make a sourdough that would help me rise my bread without using commercial yeast,” he said. “I wasn’t really concerned necessarily with flavor.”

However, he’s thinking bigger these days, and trying to take his Boston sourdough to the next level, and when you bite into that crispy crust, the effort shows.

“I’m trying to focus on flavor and build my sour to be a little more tangy and have that nuance that people are expecting out of a sourdough,” Mercury said.

The difference is the type of flour the starter is fed, and for quite some time he was feeding Siouxsie all-purpose flour, then splitting whole wheat and all-purpose, and now, at Puritan & Company it’s back to a rye mix. The bread created from the starter is a little bit different at each location.

The flavors and Mercury’s touch are now on both sides of the river.

“When I left Oak + Rowan, my last sous chef put the label on it because I left Oak + Rowan the sour, and I took some with me, so she wrote a little label and wrote ‘Breadie Mercury’ so it currently lives with them now.”

And now, Mercury’s sourdough is the backbone of every toast on Puritan & Company’s menu, the aromatic, bulky crust and soft, tangy center delivering toppings like fresh cheese, stone fruit, and speck into hungry mouths.


“Every time I bake bread, it just feels good,” said the pastry chef. “I think it’s very rewarding, and just the smell of fresh-baked bread . . . it’s just exciting.” You can sample Brian Mercury’s tangy sourdough for yourself with the toasts at Puritan & Company, and by request in the bread basket.

Tanya Edwards can be reached at edwardstanyalynn@gmail