Preheat the oven to 170C/Gas 3. Heat the oil in a large casserole over a medium heat. Put the beef in a bowl, season with salt and pepper and rub in the flour. Add the beef to the casserole and fry for 5 minutes until golden brown. You will need to do this in batches.
Remove the meat from the pan with a slotted spoon and transfer to a plate. Reduce the heat to medium and add the butter. When melted, add the shallots and cook for 2-3 minutes until golden. Remove with a slotted spoon and place on a plate.
Add the bacon and thyme to the pan and cook for 2-3 minutes, until browned. Return the beef to the pan along with any remaining flour and cook for 1 minute.
Stir in the wine, then simmer until reduced by half. Pour in the stock and increase the heat to high. Simmer for 3 minutes, skimming off any scum. Cover with a lid and transfer to the oven. Cook for 1 hour.
Add the shallots to the casserole and cook for a further 15 minutes. Stir in the lentils and cook for a further 45 minutes.
Serve with some roast vegetables or fresh pasta vermicelli.