Making of demi-glace is well defined for me as a product of veal bones and vegetables reduced to gelly concentrate in temperature 5-10C.
Here is my demi-glace which I refer to:
Beef stock, on the other hand, has ingredient similar to demi-glace but some recipes refer to only veal bones and some to bones and meat. The final product is less reduced than demi-glace like this:
So my question is:
If some recipes refer to use beef stock as an ingredient (for example onion soup) can I use my demiglace instead? If yes, what proportion I should dissolve my demi-glace with water to achieve beef stock substitute? Also if this recipe involves reduction after adding beef stock is a point of dissolving my demi-glace with water?