Pennypacker’s is a hip addition to Magoun Square

If you needed more proof that Magoun promises to be the next hip square in Somerville — see Daddy Jones cocktail bar and slated Lowell Street T stop — Pennypacker’s pretty much seals the deal. Opened last October, three years after brothers Ryan and Kevin McGuire rolled onto the fast-casual scene with their food truck of the same name, Pennypacker’s has found its niche: serving inventive and affordable soups, sandwiches, and salads to the up-and-coming neighborhood.

The space is built for take-out — mostly kitchen, with a blackboard listing the day’s menu and a few small tables. That menu changes every single day, depending on Ryan’s whim and what’s in season. “You won’t see tomatoes in the winter,” Kevin tells us. The only constant is porchetta ($8), that luscious confection of pork belly and shoulder, slathered with garlic and herbs, and spun up like a jellyroll. Today it’s topped with cranberry mostarda — that sweet and savory Italian fruit and mustard seed condiment — to cut through the porky richness, and served on crispy ciabatta, the only bread with enough oomph to support such a sandwich.

There are two other traditions you can count on: Taco Tuesday and mac and cheese on Thursdays. The pasta is creamy, with the bite of sharp cheddar. The shells are al dente with a golden crisp topping. Today, there’s sriracha in the mix, adding a welcoming, sneaky, sweet heat. We’ll be back next week to see what riff on this classic they’ve thought up.

We sample two taco offerings, black bean ($3) and ground beef ($3.50), watching in hungry anticipation as the counterperson-cook chars soft wheat tortillas over a gas burner’s flame and tops them with a generous helping of bright green guacamole. The spiced black beans make a satisfying vegetarian filling, and the greasy, ground beef version reminds us — in the best way possible — of Ortega night growing up. We poach a few pickled onions from our grilled chicken sandwich ($8), which makes the tacos even better. The portions are hearty, but we’d happily pay a little bit more for some bright fixings to balance out the tacos.

That chicken sandwich, however, needs no help in the topping department. Juicy meat is topped with those red pickled onions, strong parsley mustard, crisp bacon, and greens on a toasted brioche bun. It’s crunchy and juicy and spicy and slightly sweet — a real winner.

Grilled eggplant sandwich ($8) is an oily decadent affair, with briny capers, squeaky halloumi cheese, eggplant, pickled onions, and muhammara, the brick-red Middle Eastern roasted pepper paste. Smears like this ensure the sandwiches stand out. Pistachio butter makes an impression on a turkey sandwich ($8). She’s not the prettiest belle at the ball, with that greenish muddy hue, but what she lacks in looks, she makes up for in creamy, roasted nutty substance. The flavor manages to turn the ubiquitous roasted turkey sandwich into something more exciting.

A velvety butternut soup is vegetal, but with savory depth. A slick of yogurt and toasted pepitas make it feel special, even in a to-go cup. Almost all the food here feels special and would be at home in a full-service restaurant, with porcelain plates and metal flatware. The only disappointment: On one visit the Caesar salad is intensely bright and lemony with plenty of zest. On another it is so over-salted it is basically inedible.

Counter service is very friendly but laid-back. With just one or two employees working there at a time, it’s a good idea to call ahead if you are in a rush or taking it to go. If not? Just show up, see what’s on the menu, and settle in for a leisurely lunch. This is “fast” food worthy of a proper meal.

Catherine Smart can be reached at cathjsmart@gmail.com.

Correction: Because of a reporting error, an earlier version incorrectly referred to Ryan McGuire.