Fish in Meat Oven / Dairy Dishes

I cooked salmon in a fleishigs oven that's not ben yomo and put it on my milchig dishes

Shalom!

Thank you for your question.

The bottom line is that your salmon remains kosher to consume.

Allow me to explain.

When a utensil or appliance was not used within the last 24 hrs., it is known as “Eino Ben Yomo,” meaning, “not used today” or “older than a day.” When a utensil has not been used in 24hrs it cannot pass on any significant taste that it absorbed from a previous use (whether kosher or non-kosher, dairy or meat) to the foods it is currently being used with.

You do not mention the status of the milchig/dairy dish upon which you placed the fish. I am going to assume that it too was not Ben Yomo, and hence, there is certainly no problem. Even if it was Ben Yomo, the fish remains kosher pareve, and the plate remains kosher dairy. But you should avoid doing such things in the future.

Allow me to add a few words about what would be the case if the oven and/or plate had indeed been Ben Yomo used in the last 24 hrs.

The Shulchan Aruch rules that a pareve food that was cooked in a clean dairy utensil may even be eaten with meat. This is true even if the utensil was used for dairy that very day! This is the general practice of Sephardic Jews.

The Rema, however, disagrees and rules that pareve food cooked in a dairy utensil that was used that very day should not be eaten with meat (and vice versa). Nevertheless, if the foods did ultimately get mixed together then they may be eaten. (I.e. someone boiled pasta in a clean meat pot that was used for meat that very day and then mistakenly added the pasta to a cheese dish.) This is the general practice of Ashkenazim but one should never intentionally cause the arrangement.

However, even for Ashkenazim, one is permitted to even initially cook something pareve, like fish or bread, in a Ben Yomo meat or dairy oven to eat with the opposite type. When doing this, one should be sure to use pareve baking pans or to at least cover the baking pans with foil paper and the like. One who wishes to do this has on what to rely.

If both the plate and oven had been Ben Yomo there would be a serious issue, especially for Ashkenazim, and the fish should not be eaten. But again, in your case, all is fine even if the plate was Ben Yomo.

OC 95:1 and commentaries. Kovets Pesakim Ve'hearot page 79.