New York City's first yerba mate bar opened about a week ago on Lorimer Street, a bright and inviting little cafe called Porteñas that not only specializes in that popular South American beverage but also serves an array of homemade empanadas and sweets such as those dulce de leche delights, alfajores.

If you've never had a cup—or a gourd—of proper mate, get ready for a truly new experience. There are four different blends available here, and though the stuff looks like tea, the taste is much more earthy and bitter. The leaves' strong flavor is complemented or tempered by your choice of fruits, flowers, or coffee grounds. You can also order your mate the El Porteño way, for which you slowly pour a liter of hot water over your mate leaves, sipping through the straw as you go, or as a straight-up Mate Cocido, or as a kind of hybrid drink like the Mate-Latte or Mateccino.

Whatever you think of yerba mate—it's not for everyone, though you should certainly try it—the food at Porteñas is excellent. The empanadas are done Argentinian style, slightly fried and then baked for a buttery, flaky crust, and currently come in five flavors. There's the Buenos Aires, which is filled with well-seasoned ground beef, the South Williamsburg (pastrami and pickled cabbage), the Austin (barbecue chicken), and two vegan options, the Greenpoint and the Portland. And the pastries and chocolates are just as delicious, especially the Alfajor, two cookie wafers stuffed with a generous schmear of dulce de leche; and the fantastic Mate Creme Brulee, complete with crackling caramelized cover.

Porteñas was founded by three women from Argentina (a Kickstarter campaign provided the initial funding) who have so many other things going on in their lives that this can only be called a labor of love. Chef Fernanda Tabares also runs an acclaimed restaurant in Buenos Aires and, in fact, is back there now, but will return to Brooklyn soon with next season's recipes. Tabares's best friend, Porteñas CEO Carmen Ferrayra, who you'll probably see working the register, is really an art curator (she's in charge of production for two exhibits at next month's Armory Show) and also owns the non-profit organization Curatorial Program for Research. And the COO, Gretel Pellegrini, who plated my food last Saturday and is married to Ferrayra, is actually a dental surgeon (bone grafts are her area of expertise) and a musician with the Argentinian "tropical-punk" band Kumbia Queers.

So what is motivating them to wade into the often-nightmarish NYC restaurant scene? For one thing, they wanted to spread the word about mate, the "tea of the gods," which is rich in antioxidants, packed with vitamins, and energizes without the typical caffeine crash. There's a strong social element to the drink as well, and the rituals surrounding sharing some mate have been a big part of the three founders' friendship. But Porteñas is also something of an empowerment project, and Ferrayra and Pellegrini are seeking to hire immigrants, minorities, and women, eventually turning over the day-to-day operation to the workers. Ideally Porteñas will expand to other branches, providing even more employment and growth opportunity.

The clean, elegant design of the space was done by Ferrayra and Pellegrini (the crisscross pattern on the wall is copied from their home in Buenos Aires), and though there's not a lot of room here, about eight people can sit comfortably at a time. A multitude of plants provides color and energy, and are meant to evoke Argentina's lush Chaco region in the north.

Porteñas is located at 557 Lorimer Street, between Metropolitan Avenue and Devoe Street, and is open Monday through Thursday from 8:00 a.m. to 7:00 p.m., from 8:00 a.m. to 11:00 p.m. on Friday, from 9:00 a.m. to 12:00 midnight on Saturday, and from 9:00 to 7:00 on Sunday (