I know that the message is in French. But what I can't understand, what does meat ("viande") have to do with this pic?

I think it should actually be 'Comment trouvez-vous votre viande', whoch would mean 'how do you find your meat'. Seeing that the lady has quite a lot of it, I think it's quite easy to figure out the sense.

Isn't it more like "Comment voulez-vous votre viande?", which is closer to what was written here and means "How to do you want you meat?"...medium sounds good to me!

That's pretty literal, but yeah... it's a lot easier to say "Quelle cuisson?" which is what you may hear if you're ordering steak/lamb/whatever.

i don't imagine anyone know the artist/source?