Eat what is put in front of you. An old woman's brain? Soup of defeated warrior's blood?
Talking against God's commandments, not keeping them, or teaching others not to keep them would be a sin. Therefore, we can be sure that Christ never would have taught his disciples not to keep the smallest of the commandments.
Someone could allege that the law would have been obsolete. Even supposing it would be so, Christ would have never talked against one of God's commandments, until with his death and resurrection “it would have been obsolete”, according to the ones that think as such. Therefore, he who wants to suppose that God's law is obsolete, needs to admit that it would never happen before crucifixion.
Analyzing this we can be sure that in the following passage Christ is not ordering his disciples not to keep the law, for if he had done it he would have sinned and could not have saved us.
“7 And in the same house remain, eating and drinking such things as they give, for the laborer is worthy of his hire. Go not from house to house. 8 And into whatsoever city ye enter, and they receive you, eat such things as are set before you” (Lk 10:7-8)
It is reasonable then to think that Jesus is not ordering his disciples to eat whatever is put in front of them, in the sense that they should eat the meats that God had forbidden, but rather to eat what was put in front of them in the sense of humility, of not expecting banquets of specialties.
Let's remember that at the beginning of Christianity, the disciples only preached to other Jews. Therefore, the food they would see in front of them would be Jewish food, according to God's law. That's why he says, “eat what is put in front of you”. The Lord was not ordering his disciples to eat the brains of an old lady who died in some cannibal tribe, just because someone put it in front of them.
A similar case, and using almost the same words, is presented by Paul in I Corinthians 10:27. In this case one must realize that Paul, just like Christ, is not telling the disciples to eat human flesh if a cannibal put it in front of them. What Paul is saying is that from what God allows us to eat they could eat. A Christian missionary was not forced to drink a soup made with the eyes of the enemies that killed the tribe where he was preaching. Or drink a soup made with the blood of the decapitated enemies.
“If any of them that believe not bid you to a feast, and ye be disposed to go; whatsoever is set before you, eat, asking no question for conscience sake”. (I Co 10:27)