If I open a cafe or restaurant and I want to serve ready made kosher meals from a supplier, will jews eat from a plate that was washed with other plates ?

Hello,

I would happily order ready made kosher meals which are packaged to avoid cross contamination but feel really rude to serve it in a packet rather than a nice plate.

What is the ruling on this as I heard or read that it is not Kosher to cook with pots and vessels that have ever been in contact with food that is not combined or not kosher certified.

Thank you for your time.