BROWN THE BEEF AND ONION in oil in the open pressure cooker. Add salt and pepper, 1/2 cup wine, seal cooker and cook at 10 pounds pressure for 15 minutes per pound. Reduce pressure, open cooker and remove meat. To make gravy, remove all but 2 tablespoons fat from the cooker, add the flour and stir for 1 minute, then slowly add the wine and stock and simmer for a few minutes until thickened. Season gravy with salt and pepper to taste.