I guess "beaten path" has a range of meanings. It's hard for me to think of anything on 10a, 25a, 30a, 65a, or Juarez as being off the beaten path since those are either right downtown or are major thoroughfares with more traffic per hour than cars in my entire hometown.
El Moro, despite its location, has always seemed to me very much ON the path beaten to its door by so many divers over the years and La Perlita is similar. Anyone would agree it's not a place you're just going to stumble upon in your perambulations.
On some forums, OTBP means "farther than an easy walk from the cruise pier". By that definition, almost everything on my list would count.
Some people mean "I'm unlikely to see other foreigners there". Given the number of expats living on the island, there may not be very many such places at all.
Maybe a good definition would be "doesn't cater primarily to foreign visitors". A few on my lists do (Kinta, Kondesa, La Cocay, No Name...) but some of those are very worth visiting.
By my own subjective definition, almost everything on my lists is completely on the beaten path (El Paste might be an exception). They're the places we go and like. I provided the lists so as not to be accused of suppressing restaurant discussion. My wife feels completely comfortable going to any of them on her own.
DjDiverDan, the cochinita (and lechon) places that run out before you get back from diving are probably open before you go diving. Locals buy early to serve later in the day.
I haven't yet added Camacho's Tortas to the above list under Supper. It's on 30a and Calle 25. Since the lamented demise of Los 3 Gatitos this has been the best place I've found so far for panuchos and salbutes. They also do good sopes and tostadas. Unlike Hanal-Ki, they always get the order right (Hanal-Ki got everything right once; my son texted me with the news).
It was mentioned above, but I think it's time for me to add Nando's Hotdogs to my list as well, given that we rarely go a week without stopping there for a ham (not bacon)-wrapped hot dog with great toppings. They have a cart that's typically on 10a and Calle 3 (or is it 5?), but we go to the mothership on Q. Roo (Calle 7) near Coldwell (30a Av).
I might add Miss Dollar on 20a for lunch, but someone told me it had recently closed.
There are literally hundreds of places I haven't been. My lists include places that many others also mention, and nothing really "new".
My lists don't include a number of places others like (El Foco, Casa Mission, Sorrisi, Al Pie del Carbon, Sushi and Breakfast, Las Tortugas, anything with Lobster in the name, etc.) because I'm just not a fan. I can't recommend other places because I haven't been there (pretty much anything American-style, most Italian places, most beach bars). There are some places (El Chino Marinero, Quetzadillas, Postrecito, Carnitas Diaz on 30a or 65a, a few others) that are promising but where I haven't been enough to form a clear opinion.
So, does anyone have any new place to recommend that hasn't already been mentioned in this thread? I'm particularly interested in hearing anyone's experiences with Costillas Billy on 65a near Calle 19.