In a saucepan, heat olive oil.
Add chopped red onions and cook until they start to caramelize.
Next, add minced garlic and cook for about 2 to 3 minutes.
Deglaze the pan using white wine.
Add Worcestershire sauce and stir.
Pour beef broth and beef base and stir.
Bring it to a boil and reduce the heat to let it simmer for 3 minutes.
Remove the pan from the heat and strain the broth.
Return the strained broth to the saucepan, and add flour.
Let it simmer for about 5 minutes until the jus starts to thicken up.
Serve or keep warm in a crock pot or slow cooker until you are ready to serve.