Sauté the onion and garlic for a few minutes.
Add the carrots, celery, and mushrooms and sauté until they start to soften slightly. Season with salt and pepper, to taste, and the Italian seasoning.
When the mushrooms start to brown, deglaze the pan with your red wine. Scrub the bottom of the pan and let the wine simmer for 1-2 minutes.
Add the bouillon cube, balsamic vinegar, brown sugar, soy sauce, and bay leaf. Cook until the bouillon cube has dissolved and the the soup has come to a nice boil.
Add back in the browned short ribs.
Pressure Cook on High for 45 minutes. Let it naturally release for 15 minutes. (One hour total cook time).