Born from the namesake rabbi’s pushcart in 1910, the soft, house-made knishes at this shabby LES warhorse, baked in a basement brick oven and hoisted upstairs via dumbwaiter, are a taste of bygone New York. The old-world nosh, a thin dough shell filled with potato, comes savory (kasha, red cabbage) and primed for spicy brown mustard ($3.50) or sweet (blueberry, chocolate) and filled with cheese ($4). Make it a meal with a platter pickle and coleslaw ($1.50), and wash it all down with a fizzy cherry-lime rickey ($2.50).