When I was in Vietnam, we had not much choice in kosher food. You could ask for kosher C-rations, but in the end you got what they distributed, even if it was Spam and a few crackers.
Now to my question. I had something there called French Tartar. It is uncooked ground beef with lots of onions and salt on a French bread. I am certain, that meat was not kosher. However, now I can get kosher ground top sirloin. Can I make a “kosher” tartar sandwich with that or do I really have to cook it first?

You are allowed to eat raw kosher meat.