Here is a quick list
The bests cochinita tacos at El Turix on Emilio Castelar going towards Mazarik I am not kidding THE BEST !!!!!!!!!!!!
Fantastic habanero salsa they only serve panuchos, tortas, and tacos all Cochinita , It's across the sreet from I'l Punto Italian restaurant. Walking distance from the Hotel.
Tacos El Farolito on Newton has great carne asada , costilla and chuleta ask for the special salsa. It's cooked over charcoal one of my favorites.
Los Panchos has some of the best Carnitas In DF the caldo de pollo is good to they have a dish called petroleras that is like a giant sope very good. You probably need a a cab to get there from the Niko.
Almost across the steet is El Bajio a great Traditional Mexican restaurant that features food from Veracruz, don't miss the plantan empanadas filled with black beans.It's on Campos Eliseos and Alejandro Dumas. If you want fancy try Pujol Mexican or Biko Spanish. I haven't been to the W restaurant Solea but the chef there is getting good reviews. Also an all time classic in Polanco are the Conchas (Mexican pastry) at Bondy also very close to the hotel., they run out early.
Los Panchos, Calle Tolstoi # 9, Colonia Anzures, is said to be good (and authentic). I was there years ago but only had some caldo de pollo. (I was not feeling well that day.)
Nick Gilman, in his guide book, "Good Food in Mexico City", notes the carnitas are among the best in the city.
What food do you expect to find in Mexico City, in the Polanco neighborhood particularly . . . other than "authentic." There's no one type of Mexican food - the variety is unending. Is there something particular you're looking to try? There are scores of restaurants in that upscale neighborhood, some of which are mentioned in other archived discussions on this forum - just wander about and sit down at a place that looks interesting to you.
If you want some 'street food' just take the underpass from the backside of the hotel - walk underneath Paseo de la Reforma - and come-up on the other side (facing 'Auditorio Nacional') and patronize one of the half-dozen or more vendors who set-up there daily. In the a.m. you can get some tamales and atole there, for breakfast.
Have a great visit.