1 onion, skin on, halved
250g/9oz baby spinach leaves
1 pinch freshly grated nutmeg
250ml/9fl oz beef or veal stock
2 tbsp vegetable oil
115g/4oz butter
175g/6oz duck liver 辫芒迟茅
4 x 200g/7oz beef fillet steaks
150ml/5fl oz Madeira
4 slices brioche
150ml/5fl oz red wine