Cook shallots in a seasoned saucepan until they turn dark golden. Be careful not to burn the shallots or your final jus will taste very bitter.
Add the wine and port and simmer until the bitterness of the alcohol is cooked out and the syrup has reduced by about three quarters of the original amount.
Add the beef stock and leave to simmer.
Once it has reduced enough, it will coat the back of a spoon, or hold its shape dragged across a plate -be careful, there is a very fine line here; not enough, and your sauce will end up looking watery, too much and it will taste bitter. Your jus should taste sweet and flavourful.
Add rosemary and thyme and leave to infuse. This is just for extra flavour.
Taste and adjust to perfection -if it’s too sweet, add a little lemon juice for extra acidity to balance it.
Pass the jus through a very fine sieve to finish and served warm with meat and vegetables.