As recipe says, toss in flour, seal in the pan and then gently gently gently cook in stock for as long as you have got....an hour, even more. Braising steak can be very tough, hence the long slow cooking, but as your recipe suggests, if you cook it gently once it has sealed, for a long time it will soften considerably and be very tasty. I try and cook mine in the morning for about an hour, though often a lot more like 2 hours, then leave in its juices for the day till I am ready to combine in the pie. I think it benefits from the resting time.
Sounds like a good pie!