Heat bacon and half the lard in a large saucepan over medium heat and stir occasionally until fat renders (3-5 minutes). Add shallot and stir until tender (3-5 minutes), add garlic and stir to combine.
Meanwhile, heat a non-stick frying pan over medium-high heat, add beef in batches and turn occasionally until browned (3-5 minutes), then add to shallot mixture. Deglaze pan with brandy and 150ml wine (be careful as brandy may ignite), add to beef with remaining wine, stock and thyme, season to taste and bring to the simmer. Reduce heat to low and simmer until meat is just tender (1½-2 hours).
Meanwhile, heat remaining lard in a frying pan over medium heat, add onions and stir occasionally until golden (3-5 minutes). Add to beef and cook until tender (20-30 minutes).
Meanwhile, mix butter and flour to a paste in a small bowl, add a spoonful of beef sauce and stir to combine, then return to beef mixture and stir until thickened slightly (5-10 minutes). Serve hot with buttery mash.