Kelim

Question

I read your reply about eating kosher food withnon-kosher utensils (e. g., if you have a kosher meal at a hotel.) You say that since we have the principle of setam kelim einam benei yomam it is no problem. But what if your kosher meal has onions in it? Would you then be required to use the plastic utensils (since if I remember correclty, a davar charif brings out the non-kosher taste even after 24 hours)? If not, why not. Thanks