Reduce heat to medium. Add Butter to the pan, allow to melt and get hot. Add Onions, lightly season with Salt, Pepper, and Garlic Plus, sauté for 4 minutes. Add Mushrooms, sauté for 5 minutes. Make a well in centre of pan, add a little Olive Oil if required, add Garlic and sauté for 30 seconds, (until aroma builds).
Deglaze fry pan with Red Wine, allow Wine to mostly reduce.
To a pressure cooker add Stock, and Tomatoes. Add Celery, Carrots, Salt, and Pepper. Lay Beef on top of Vegetables. Add Mushroom Sauce on top of Beef.
Pressure cook for 45 minutes.
Remove Beef, set aside leaving Vegetables, and liquids.
Roux:
- In a small skillet on medium heat, add Butter. Allow Butter to melt and get hot, simmer 3 minutes, (until frothing slows). Add in Flour, stir constantly for 3 minutes.
Add Roux to the pressure cooker, mix until Sauce thickens.
Serve with Mashed Potatoes.