You may eat any clean bird. (Deuteronomy 14:11)
The literal commandment is that we may eat any clean bird.
Messiah implicitly affirmed this commandment when He spoke about the Law:
"Do not think that I came to abolish the Law or the Prophets; I did not come to abolish but to fulfill. For truly I say to you, until heaven and earth pass away, not the smallest letter or stroke shall pass from the Law until all is accomplished. Whoever then annuls one of the least of these commandments, and teaches others to do the same, shall be called least in the kingdom of heaven; but whoever keeps and teaches them, he shall be called great in the kingdom of heaven. (Matthew 5:17-19)
Some have asked about Mark 7:19. Messiah was speaking of ritual impurity resulting from eating bread with unwashed hands. We recommend this detailed study of that passage if you have additional questions.
G-d created the heaven, the earth, the sea and everything that is in them. (Psalm 146:6) He did so with an intended structure and order. Part of that intended order was that certain birds were created for food and other birds were not. This was recognized from the beginning as even Noah recognized the difference between clean and unclean animals (Genesis 7:2-9).
In a similar manner, there is a certain individual in G-d's order who would save the world from sin: the Messiah Yeshua. There is no other person intended for that purpose. Attempting to find salvation in anyone (or anything) else is akin to eating a bird not intended for food or intending to marry your sister: G-d says 'no'.
We know that Messiah did not sin (Hebrews 4:15) and so we know Messiah fulfilled this commandment by examining the signs of fowl to distinguish between those which are kosher (suitable or proper) and non-kosher (improper).
Traditional observance of this commandment is found in its literal sense: examining the signs of fowl to distinguish between those which are kosher and non-kosher. The details of those signs are found in Leviticus 21 and Deuteronomy 14.
We are able to fulfill this commandment today and should examine the signs of birds/fowl to distinguish between those which are kosher and non-kosher.