Laurent Tourondel is pretty busy these days. Not only will he be opening an American brasserie in the Cassa Hotel and Residences at 70 West 45th Street, but he has also become a consultant to Ralph Lauren for Ralph's restaurant in Paris. (Danny Meyer originally consulted on the project.) "He will be executing Ralph's perspective and vision,'' confirmed a rep for the designer. The association makes sense, as both men celebrate iconic Americana — Lauren with his flag sweaters, jeans, and cowboywear; Tourondel with his steakhouses and fifties malt shop. "I think I'm the most influential French person who represents American food in the United States,'' said Tourondel, who will change some dishes and introduce new recipes at the already-popular bistro. "I am very honored that he chose me to do this.''