Dunkin’ Brands Inc., a portfolio company of Bain Capital LLC, Carlyle Group and Thomas H. Lee Partners LP, has sold California sandwich chain Togo’s Eateries Inc. to San Francisco private equity firm Mainsail Partners for undisclosed terms.

Togo’s sandwich shops saw more than $150 million of systemwide sales last year, said Jason Payne, a managing partner at Mainsail.  The sale was announced Dec. 3.

Canton, Mass-based Dunkin’ Brands, the parent of Dunkin’ Donuts and ice cream chain Baskin-Robbins was take private in March 2006 by Bain, Carlyle and T.H. Lee for $2.5 billion.

In October 2006, Dunkin’ announced its plans to sell Togo’s, tapping Trinity Capital LLC to shop the sandwich, soup and salad chain.

“We did a broad auction, marketing to well-capitalized operations and midmarket private equity firms,” said Kevin Burke, a managing partner at the Los Angeles investment boutique.

Trinity’s Ben Cary was the lead banker on the deal.

Overshadowed by two huge brands, Dunkin’ Donuts and Baskin-Robbins, Togo’s had no received the attention level it needed, according to Payne.

Dunkin’ Donuts and Baskin-Robbins each have a national footprint, though Dunkin’ Donuts has a traditional stronghold in the Northeast.

Togo’s operates solely in the western U.S. Most of its stores are in California, with a few in Arizona and Washington.

“I grew up in Northern California eating Togo’s sandwiches, so I was aware of the brand,” Payne said.

Togo’s got its start in 1971, when Michael Cobler purchased a sandwich stop in San Jose, Calif.  He built it into a franchise before it became part of Dunkin’ Brands in 1997.

The target now has 261 stores and serves more than 50,000 customers a day, said Payne.

Togo’s is Mainsail’s first restaurant deal, but the transaction is in line with its investment model of teaming with industry veterans.

The firm tapped Tony Gioia, a former president of Baskin-Robbins, to head Togo’s business as chairman and CEO.  Gioia was Baskin-Robbins president Allied Domecq plc owned Dunkin’ Brands.  During this time, he also sat on the company’s retailing executive board.

Mainsail invested in Togo’s from a $100 million fund, the second vehicle the firm has raised since it was founded in 2003.

For legal advice, the sponsor tapped Kirkland & Ellis LLP.

Ropes & Gray LLP advised Dunkin’.

Bain and Carlyle declined to comment on the deal, while calls to T.H. Lee were not returned.

A call to Dunkin’ Brands also went unreturned.