Preheat your oven to 200°C/Fan 180°C/Gas 6. Set a roasting tray in your oven to heat up. Slice 1cm off the top (the pointy end) of the garlic.
Rinse the barley. Place in a lidded pot. Pour in 500ml water and a pinch of salt. Bring to the boil. Reduce the heat. Cover. Simmer 25 mins or till the barley is tender. Drain. Let it steam through for a couple of mins.
Peel your the and cut into 2cm chunks. Toss into the warm roasting tin with 1 tbsp oil and a good pinch of salt and pepper. Nestle the garlic bulb in the centre. Roast 20 mins, turning half way through cooking, or till golden and tender.
Whisk the honey and mustard with 1 tbsp olive oil. Season to taste. Set aside. Remove the parsnips from the oven once cooked. Pluck the garlic bulb from the pan. Cool a little. Then, squeeze the cloves out and fold through the cooked barley.
Grate the lemon zest over the parsnips while they’re still warm. Add a pinch of chilli powder and the leaves from the thyme. Toss well. Season with salt and pepper, to taste.
Spoon the cooked and drained barley over and mix it and the honey mustard dressing together. Add a good squeeze of lemon juice to the mix. Toss in the lamb’s lettuce. Season to taste. Serve warm or cold.