Your glazed ceramic plate probably isn’t coated with anything weird, but since it’s a matte glaze, it’s also not the best for food surfaces. 

Mattes look matte usually because they are rough surfaces on a micro scale. They can be more difficult than gloss glazes to get thoroughly clean of food particles, and can hold on to odors and stains. I used to use a matte tea mug long ago that taught me this lesson… I had chai in it a few times and then the spice smell never washed out. 

I always glaze my pieces with a shiny glossy glaze on food contact surfaces. Let me know if you’d like me to make you something for your steaks sometime! 

 I might be up for that. Been a long time since I've bought artisan ceramics. Will give me something to think about anyway!