Heat your oven to 200°C/Fan 180°C/Gas 6. Chop the leaves and stalks off the carrots. Set the leaves
to one side. Scrub the carrots and beetroot. Slice the beetroot into 1cm-thick rounds. Cut the carrots
in half lengthways.
Lightly crush 2 tsp coriander seeds in a pestle and mortar (or use a small bowl and a jam jar). Place the veg on a baking tray. Drizzle over 1 tbsp olive oil. Scatter over the coriander seeds with a pinch of salt and pepper. Toss together. Drop on the garlic cloves, unpeeled. Roast for 40 mins.
While the veg roast, tip the barley into a pan. Cover with 500ml boiling water. Pop on a lid. Simmer for 20 mins till just tender. Drain, tip back into the pan and leave to cool.
While the barley cooks, peel and thinly slice the onion. Zest and juice the orange and lemon into
a bowl. Whisk in 2 tbsp honey and season. Add the onion and toss to coat. Leave to pickle.
When the veg have roasted for 30 mins, set a griddle or frying pan on a high heat. Toss the chicken fillets with ½ tbsp olive oil and a pinch of salt and pepper. Place them in the pan and cook for 4-5 mins on each side till cooked through. Scatter over 2 tsp cumin seeds and cook for a further 1 min. Place them on a plate.
Quarter the avocado and scoop out the flesh, discarding the stone. Wash the carrot leaves
well. Finely shred a small handful of them. Spoon the onions into the barley, leaving most
of the citrus liquid in the bowl. Add the carrot leaves. Stir together, taste and season.
Pluck the garlic from the veg tray and squeeze out the flesh. Stir it into the reserved citrus marinade. Add the chicken fillets and stir to coat them.
Arrange the watercress on a serving platter or a couple of plates. Pile on the onion barley, roast veg and the chicken. Pour over the citrus dressing. Finish with the avocado quarters and serve.