Thanks for letting us know of this new place, advertised as "the best authentic Columbian restaurant in New Haven". Since it is the only one I know of in town, the prophecy is self-fulfilling! I arrived about 1:30 for a late lunch, and there was only one other table occupied.
The room seats about 40, plus what appeared to be a bar in a back alcove, but the lights were out there so I'm not sure. The decor is clean but unassuming, with some vaguely spanish watercolors on the walls. I decided to try the Bandeja Paisa (Country Platter?) and soon found that the Columbians, like the Brazilians, enjoy a surfeit of protein. A large plate arrived with a thin steak topped with a fried egg, a mildly spicy chorizo sausage, a huge crusty bacon slab, a slice of avocado on a fried plantain, plus frijoles and arroz. The steak was a little tough so I wished I had gotten the pork or chicken variation, but everything else was fine. The wine list only had six rather ordinary wines plus sangria, and since I had a long drive ahead, I passed on alcohol and had tea instead. The waitress was friendly and there is a private parking lot on the south side of Grand Avenue between Olive and the expressway. Their menu (available at www.lacascadanewhaven.com) has many meat and seafood offerings, and according to a review on another site, they can arrange for a vegetarian plate as well. The prices are quite reasonable for the size of the servings.