The ever-improving Sidecar Bar, a pioneering gastropub in Graduate Hospital, took another step forward this fall with the addition of chef Brian Lofink. Formerly co-chef at Matyson off Rittenhouse Square, Lofink hasn't upscaled Sidecar's inventive bar fare so much as tweaked it with better ingredients. His nachos - usually a dish I dread - were an irresistible example. The gooey jack cheese has been replaced with a genuine Mexican melter - asadero. The salsa, a green tomatillo zinger studded with pineapple, jalapeño, and cilantro, was inspired by Lofink's brief stint with Bobby Flay. The stellar meat topping is Lofink's rendition of pork carnitas, slow-braised to tangy tenderness with chipotle, citrus, and wine.