Barro Negro is great place to sample a variety of Oaxacan moles. We went about 8:30pm on a Monday…read morenight. The restaurant was pretty much empty so we were seated immediately. The interior is pretty plain, with some Oaxacan art on the walls, apparently available for purchase.
We were served tortilla chips with samples of 3 moles (Negro, Coloradito and I think the 3rd was Mancha Manteles) and 2 salsas. As my wife and I primarily went to Barro Negro to sample moles, it was great that we could taste them before committing to a full entree. They were all very good and very different. If you think all moles are 'a Mexican chocolate sauce,' then you'll be surprised at the different varieties. The salsas were all very good and on the spicy side.
For entree, I ordered the Mole Coloradito and my wife got the Mole Negro. Both were served with a chicken leg/thigh quarter covered in a very generous pool of mole, along with a small amount of rice and beans. For me, it was the right amount of mole (a lot!) and rice and beans (a small portion of each). The Coloradito is a sweeter mole, very smooth and rich. It was excellent. The Negro is smoky, almost burnt tasting. I happened to know that the cooking process includes burning chile seeds and adding them to the mixture. To me, it was kind of ashy and not to my taste. My wife said that she really liked it and the flavor mellows as you eat more. At any rate, if you're familiar with Mole Poblano, which is also very dark, the Oaxacan black mole is a totally different dish.
As it was late, we chose not to get any dessert. The service was attentive and quick, not surprising given that the restaurant we empty. We enjoyed our food very much and highly recommend Barro Negro for sampling Oaxacan moles.