These directions are for using a Dutch Oven. I will give pressure cooker instructions at the end of this.
In a bowl, mix the flour, salt and pepper.
Pat your stew cut beef dry and dredge in seasoned flour, salt & pepper.
Heat a thin layer of oil in the Dutch Oven on very high. When the oil shimmers, sear the meat for about 3 minutes (don't touch it) until is has a golden crust. Turn the meat, and sear.
Don't crowd the meat! Sear in batches, if necessary. You want lots of brown "fond" on the pan-- that's where the flavor is. Remove the meat and set aside in a bowl.
Add a little more oil (1 Tbsp) and add the onion, celery, carrots and mushrooms (if using) and saute for about 3 minutes. Add the garlic (careful not to burn).
Push the veggies aside to show all the brown fond (that crusty stuff on the bottom of the Dutch oven) in the pan, and pour 1/2 cup red wine with the heat on high-- this is to deglaze the flavor in the brown color.
Add the tomato paste and work into the wine.
Add the beef stock, thyme, Worcestershire, and taste for salt & pepper seasoning.
Add the potatoes, and return the seared meat to the pot. Lower heat to simmer and cover with a lid. Simmer for at least an hour...
I find that Russet potatoes give enough starch to thicken this stew. If the gravy is too thin, you can thicken by adding about a scant tablespoon of cornstarch, in a bowl, and add a little bit of the stew liquid. Whisk into the stew to thicken.
Don't forget fresh French bread to soak up the gravy!
Or, add to a slow cooker and cook for 4-6 hours.
Brown the meat and remove to a bowl. Add the vegetables, and cook until soften. Add the garlic and stir. Push the veggies aside, and add the tomato paste and thyme and cook for a minute or two. Add the red wine and deglaze in the pressure cooker. Add the broth, Worcestershire and return the beef to the pot. Use the STEW button (35 minutes). One the timer beeps, release the pressure, and then stir in the peas and serve.