Breakfast and lunch have a lowly reputation in the food chain, Matthew Cahn explains.

They're often the "middle child" to dinner.

So happens that Cahn himself is a middle child — the 28-year-old son of Cherry Hill Mayor Chuck Cahn and his wife, Stephanie, sandwiched between David (a doctor) and Liz (a grad-school student in public health).

Speaking of sandwiches: On Friday, Oct. 20, Cahn opens a mini-diner/takeout called Middle Child at 248 S. 11th St. in Washington Square West. He's taken the narrow storefront previously occupied by Petit Roti, adding a six-seat dining counter and about 10 seats for his homage to the luncheonette.

There also are shelves stocking a quirky selection of some of Cahn's favorite foods, such as Duke's mayo, Marshmallow Fluff, Quisp cereal, and Hammond's pretzels, and house-brined pickles in the case.

Cahn — a front-of-the-house veteran of such New York establishments as Court Street Grocers and Superiority Burger who fell into the restaurant biz after working in advertising — has the services of Keith Krajewski, most recently executive chef at Marigold Kitchen. Krajewski has packed away his tweezers; there's no need for precious plating, given the menu that he and Cahn have cooked up.

It suggests "Philly diner," but adds a contemporary spin.

For breakfast (served all day), the house egg-and-cheese sandwich may come gussied up with arugula, but there's also a simple plate of eggs, hash browns, and choice of toast for less than $6. Then again, there's also blintz toast — a riff on blintzes that has whipped farmer's cheese, blueberry-masala jam, and lemon zest on potato bread.

They're serving Elixr coffee, and (for now, anyway) his mother's pastries.

Lunch menu includes a Reuben, a turkey-and-Swiss sandwich (but with blueberry-masala jam and arugula), a grilled cheese sandwich, and a vegan banh mi-ish sammie dubbed the Phoagie. It's hoisin eggplant, avocado, white onion, bean sprouts, fresh and frizzled onions, Viet herb mix, pho sauce, and sambal chili paste on a Sarcone's hoagie roll ($9).

All meats and condiments are prepped in-house.

Hours are 7 a.m. to 3 p.m. Tuesday to Sunday.