Tried Casa B tonight--officially their first night open. It's two or three doors down from Ronnarong, very sleek decor, with space in the basement and at ground level. DC had sangria, I had a well-made periodista. The tapas are Latin-inspired rather than Spanish but quite tasty. High points were the wild mushroom pinchos and the cod fritters. They start each meal with complimentary plantain chips and asparagus dip. Definitely a nice addition to the Union Square offerings!