Downtown lunch spots are welcome additions

Z Square's tuna sandwich on multigrain bread. (Wendy Maeda/Globe Staff)

If there's anything a downtown lunch spot requires for success, it's a smooth operation. A lunch break is only so long. It might seem insignificant, but getting lunch fast enough to allow five minutes in the sun is just what's needed before facing an afternoon of air conditioning and e-mail. Hey, Z Square in the Park: I want my five minutes back.

The third location of the Z Square chain (the others are in Harvard and Kenmore squares), Z Square in the Park opened just over two weeks ago in the pretty solarium in Post Office Square, located in a former Milk Street Cafe outpost. Z serves a small-but-growing menu of sandwiches, panini, soups, and salads. It's the kind of food owner David Zebny says he wanted to eat during his 15-year tenure working in Post Office Square.

Despite many tasty items on the menu, the new spot hasn't yet figured out how to efficiently move customers in and out. They have expediters but they're not solving the problem. Striking white tiles and a counter-in-the-round look beautiful but set the stage for some disorganized lunchtime drama. Everyone is nice, but why, on two occasions, do they take so long to give our ZLT to someone else?

And that ZLT ($8), even with its cute name, is one of the less successful items. The mix is bacon, lettuce, tomato, and avocado. One day, too much chewy bacon is piled on overripe avocado. Another, an itty-bitty portion of bacon takes a back seat to greens and an abundance of mayo. Better (and faster) choices are the daily pressed sandwiches ($7), whose fillings rotate throughout the week. Goat cheese and roasted vegetable ($6.50) has a great balance of meltiness, tang, and texture; a pressed muffaletta ($7.50), with mortadella, salami, provolone, and olive salad spread, is a rich, savory delight.

Also good are Mediterranean tuna ($8) on multigrain bread - tasty, basic, and easy to like - and Z Square's take on a chacarero ($9), the Chilean sandwich popularized by the Downtown Crossing take-out spot. Piled on a soft roll, sliced flank steak, green beans, avocado, Jack cheese, and chimichurri sauce are a killer combo. It's smaller and more expensive than the chacareros sold down the street, but it's delicious and the setting is nicer.

Z Square is off to a good start. But with nearby competition doing similar things faster and less expensively, the well-situated cafe needs to streamline lunch service, quick.

In terms of moving people along, Z Square should look to the Carving Station for ideas. This year-old deli, which specializes in hand-carved meats, gets good food to you promptly, a lesson owner Laurence Wintersteen says he learned from running nearby Pressed Sandwiches.

The Carving Station is a solid concept. Meats are roasted in-house and carved to order, and sides like mac and cheese, potato salad, and baked beans are made from scratch. Even the chips, seasoned and baked tortilla triangles, are homemade - and addictive. But along the way from concept to execution, there are a few disappointments.

Our lunch group is excited by the prospect of pulled pork, but the meat is too sweet and flabby. Along with a weepy, mayo-heavy potato salad, the sandwich sits uneaten. In a subsequent visit, we stick to the basics: tasty roast chicken ($7.50) and the Reuben ($7.50), with layers of thinly sliced corned beef and a judicious application of Russian dressing. Both are worth returning for.

If the Carving Station scaled its long menu back a bit, they could focus on stand-out items like the ham and egg sandwich ($7.50), in which thick slabs of ham are stacked with hard-cooked eggs, cheese, and a lively yellow pepper ketchup on a puffy wheat bun. Big and unwieldy - but yum. There's something both unusual and familiar about this satisfying sandwich.

The Carving Station and Z Square are both welcome additions to a humdrum downtown lunch scene. With a few tweaks to the menu (Carving Station) and service (Z Square), both could earn their midday lines.

But the best way to maximize your time at lunch is to get your five minutes in the sun before your food. Then you know that before you head back to the office, at least something went right.