Leviticus 11 contains dietary restrictions, but they are not Kosher. For instance, the Talmud says that one must not eat a calf which has been boiled in its mother's milk. Rabbinical law forbids the consumption of any diary product at the same time as the consumption of any beef product.
Jesus argued that the essence of the law was love of God and love of neighbor; such expansions of the law made the law burdensome to follow. Jesus also argued that we must keep in mind the purpose of the law: Man is forbidden from labor on Sunday so that he might have that day reserved to glorify God; when Jesus glorified God by curing a sick man, the rabbis criticized him for "violating" the law. Jesus argued not that it was OK to violate the law, but that what he had done fulfilled the spirit of the law; the rabbis were, according to Jesus' logic, taking a single verse out of context.