Mimi’s Café president Phil Costner has been working on turning around the 143-unit chain since Le Duff America bought it from Bob Evans Farms Inc. in February. As he prepares for the Sept. 9 launch of the chain’s new breakfast menu and the Oct. 7 introduction of new lunch and dinner menus, he said he’s confident that Mimi’s will return to its glory days.

“In the next 18-24 months, I think we’re going to engineer one of — if not the — greatest comebacks in our lifetime,” he said.

Costner said the three-daypart chain has seen average unit volumes fall from $3.5 million to $2.5 million in the past five years due to what he views as mismanagement from its previous owners, who moved the chain away from its casual-dining roots.

“It’s pretty clear that the direction from the prior ownership was very explicit, very direct, and that’s what specifically repositioned Mimi’s as a family-dining house and vacated the casual-dining segment,” he said.

But Costner praised the staff he inherited from Bob Evans, and he said he has retained most of the key executives, including corporate chef Katie Sutton, who replaced Adam Baird shortly before the purchase, vice president of culinary research and development Anna Ohki, and vice president of marketing Karen Eadon.

His only major new hires are vice president of operations Stuart Gee, formerly vice president of operations services at T.G.I. Friday’s, and Scott Miller, another Friday’s veteran, who is the new vice president of finance.

Costner and his team have been working on the new menu for the past four months and have been using the Mimi’s Tustin, Calif., location as a laboratory. That unit is one of the chain’s top-performing restaurants, Costner said, and is also located near Mimi’s research and development center.

Over the past couple of months, the chain has tested new menu items with “real customers spending real dollars with real servers,” Costner said. Based on their feedback, they made changes every week.

He also has reduced the number of microwaves in the restaurant from four to one.

“Our position is [that] traditionally prepared, authentic French-American cuisine does not come out of a microwave,” he said, adding that a microwave doesn’t generally save time. “In a vacuum it does, but if you’re spending three or four minutes preparing a sauce, the advantage of cooking the pasta in a microwave is meaningless.”

Costner said he is working with Le Duff’s vendor partners to streamline the cooking process for Mimi’s new items while also improving their quality.

For example, the new dinner menu will feature bouillabaisse with sautéed scallops and prawns, mussels, potatoes and tomatoes, sprinkled with chopped parsley and toasted baguette. The broth, made with white wine, fish stock, potatoes, tomatoes and seasonings, is produced by the same supplier that makes all the soups and sauces for La Madeleine, another Le Duff brand.

At the restaurants, the cooks will sauté the scallops and prawns in olive oil and the mussels will be steamed open with wine. They’ll be placed in a bowl and the portioned, pouched broth will go over the top.

“It’s a classic dish that looks incredibly complex, but we’ve constructed it in a way in which it’s on the simple side of the simplicity meter and the high side of the consistency meter,” Costner said.