Hi,
Go to Elementary POS Office (I recommend to use notebook or big tablet):
https://app.elementarypos.com
Menu->Sales items settings->Items
Select sales item.
Click on the "Stock" tab and select "Recipe: Reduce stock items when
selling."
Then you can link some stock item, for example egg and other ingredients.
When a sales item is sold, the stock items entered are deducted from the
stock.
How to create a stock item:
Menu->Sales items settings->Stock items->New stock item.