2 medium carrots, trimmed and thickly sliced
2 celery sticks, trimmed and thickly sliced
800g/1lb 12oz floury potatoes, preferably Maris Piper, peeled and cut into roughly 5cm/2in chunks
1 medium onion, thickly sliced
2–3 bushy sprigs fresh thyme or ½ tsp dried thyme
1 heaped tbsp plain flour
1 large bay leaf
sea salt and black pepper
2–3 tbsp cold pressed rapeseed oil or extra virgin olive oil, plus extra for greasing
2 tbsp cold pressed rapeseed oil or extra virgin olive oil
few drops naturally brewed dark soy sauce
800g/1lb 12oz beef topside, tied (see tip)