Eglomised painting, painting best on glass, portrait of a Saint, Saint Luc and his ox

Eglomised painting ;
This is a painting on glass that is made from the back.
It figures a Saint and an ox, probably Saint Luc (Luke?) whose attribute is an ox.
The ox is considered as God émanation blowing the divine word to the Saint.
It was probably made in the Eastern countries of Europe.
It is in good condition with some wears on top, on the yellow best part of the painting.
Interesting technique where the painting is made on the wrong side.
Quite difficult to make.
Dimensions : 21/30 cm or 8,2"/ 11,7"