- 50g/2oz white mustard seeds
- 50g/2oz black mustard seeds
- 75g/3oz soft light brown sugar
- 2 tsp ground allspice
- pinch ground cinnamon
- 1 tsp coarse salt
- 1 tsp black peppercorns
- 1 tsp paprika
- ½ tsp turmeric
- 125ml/4fl oz red wine vinegar
- 3 tbsp stout
- 25g/1oz butter
- 2 large red onions, sliced
- 1 sprig fresh thyme
- 15g/½oz butter
- 2 tbsp olive oil, plus extra for dressing
- 4 x 200g/7oz fillet steaks
- salt and freshly ground black pepper
- 2 ciabatta loaves
- 2 heads Little Gem lettuce, leaves separated
- ½ lemon, juice only
- 2 large beef tomatoes, thickly sliced
- Place all of the dry ingredients into a food processor and blend until the seeds are roughly crushed. With the motor still running, gradually add the vinegar and blend until well mixed.
- Add the stout and blend briefly.
- Transfer the mustard to a bowl and leave to stand for one hour to thicken, then transfer to sterilised dry jars.
- Cover the surface of each with a disc of waxed paper, waxed side down, and leave until cold. Top the cold jars with airtight lids, label and store in a cool dark place. The mustard should keep for 3-6 months.
- Preheat the oven to 200C/400F/Gas 6.
- For the onions, heat a separate pan until hot and add the butter and oil, then add the onions and thyme. Reduce the heat and cook slowly for 12-15 minutes, until caramelised.
- Meanwhile, for the sandwich, heat an ovenproof frying pan until hot and add half the butter and oil.
- Season the steaks with freshly ground black pepper. Add to the hot pan and cook for 2-4 minutes on one side. Turn the steak over and transfer to the oven for 3-4 minutes, or until cooked to your liking.
- Remove the steaks from the pan, season with salt and set aside to rest for a few minutes. Reduce the oven temperature to 180C/355F/Gas 4.
- Place the ciabatta into the oven for five minutes, just to warm through.
- Dress the Little Gem leaves with a squeeze of lemon and a little olive oil.
- To serve, cut the ciabatta loaf in half then split it lengthwise and place onto a board.
- Cut the fillet steak on an angle into 1cm/½in thick slices.
- Spread the mustard onto the bottom of the bread, and top with the dressed lettuce.