Let begin with; Is there a commandment that says all foods are clean?

No commandment says all foods are clean. There are commandments that state all foods are not clean. In chapter 11 of Leviticus Adonai (God) defines what he considers food for humans to eat, not all that is edible is biblically clean or is food that Adonai (God) wants us to eat.

Didn’t Yeshua say all foods are clean in Mark 7:19?

18 So He said to them, “Are you thus without understanding also? Do you not perceive that whatever enters a man from outside cannot defile him,

19 because it does not enter his heart but his stomach, and is eliminated, [a]thus purifying all foods”

MaRK 7:19 nkjv

The “[a]” before “thus purifying all foods” is making reference to the fact that none of the oldest manuscripts include “thus purifying all foods”.

What does it mean by “all foods”?

Let me answer that question with a question; Was Yeshua sinless?

Sin is transgression of the Law (Torah). Yeshua was the perfect sacrifice and was sinless, he did not break the commandments of the Torah, nor did he teach others to sin.

For our sake he made him to be sin who knew no sin.

2 COR 5:21 esv

Would Yeshua teach someone to sin? No, definitely not; that would make him least in the kingdom of heaven.

Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven.

Matt 5:19 KJV

Yeshua is definitely not least in the kingdom heaven.

Yeshua was sinless, the perfect sacrifice.

Since Yeshua was sinless and did not break the Torah (Law), then his reference to all foods would be all foods that Adonai (God) said we could eat. Essentially, animals with cloven hooves and chewed the cud and fish with fins and scales. For a more through definition see Deuteronomy Chapter 14 and the 2nd witness; Leviticus Chapter 11.

Then, what does Mark 7:18-19 mean?

The key to understanding this is by examining the whole of the Mark 7. In verse 2 (see quote below), the Pharisees claim that Yeshua’s disciples were eating bread with “defiled…unwashed hands”. In the last part of Mark 7:18 (see quote below), “…Do you not perceive that whatever enters a man from outside cannot defile him”. The keyword here is “defile” you are not defiled from eating with unwashed hands. There is no commandment that says you must wash your hands before eating.

2 Now when they saw some of His disciples eat bread with defiled, that is, with unwashed hands, they found fault.

18 So He said to them, “Are you thus without understanding also? Do you not perceive that whatever enters a man from outside cannot defile him,

MaRK 7:2 & 18 nkjv

While washing hands before eating is a good sanitary concept, it is not a biblical commandment, it is a tradition of man. The Pharisees were trying to enforce it on the people. Mark 7:18-19 is not about what foods to eat but whether or not it is commanded that you have to wash your hands before you eat (defiled if you don’t).