Can mayonnaise be mixed with meat in kosher law?

No, mayonnaise cannot be mixed with meat in kosher law.

According to the rules of kashrut, meat and milk products are not permitted to be mixed or consumed together. This prohibition applies to all types of meat, including beef, pork, lamb, and poultry, as well as all types of milk and milk products, including cheese, butter, and yogurt. Mayonnaise is a dairy product, as it contains eggs and oil. Therefore, it cannot be mixed with meat or consumed with meat.

It's important to wash all utensils, knives, chopping boards and equipment that have come into contact with meat or milk products before using for anything else. It is also important to thoroughly clean your hands after handling meat.