Heat your oven to 200°C/Fan 180°C/Gas 6. Line a baking tray with baking paper. Trim the green leaves off the cauliflower (keep them to use in stir-fries or sweat them in a little olive oil with garlic as a side dish) and break the cauliflower into small florets. Roughly chop the stalk into bite-sized pieces. Tip the cauliflower into a bowl. Add 1 tbsp olive oil and a pinch of salt and pepper. Turn to coat in the oil and seasoning. Spread the cauliflower out on the baking tray. Roast the cauliflower for 25 mins.
While the cauliflower roasts, tip the pearl barley into a medium-sized pan. Pour in 450ml boiling water and add a pinch of salt. Pop on a lid, bring back to the boil, and then turn the heat down and simmer the barley for 15-20 mins till tender.
While the barley cooks, dice the tomatoes and pop them in a large, clean bowl. Peel and finely chop the onion. Add them into the bowl with the tomatoes. Stir in 1 tsp ground cumin. Finely grate in the zest from the lemon and squeeze in the juice from half the lemon. Set aside.
Tear the kale leaves off their thick cores and shred them into bite-sized pieces. Add them to the baking tray with the cauliflower. Bake the veg for 5 mins till the cauliflower is a little charred and tender and the kale has picked up a little colour.
Drain the barley, give it a shake in the colander to get rid of as much excess water as possible, then add the barley to the tomatoes and red onions.
Slice the pomegranate in half on the equator. Hold one pomegranate half loosely in your hand, cut side down. Hold it over the bowl of veg. Whack it with a wooden spoon and the pomegranate seeds should fall out into the bowl. Repeat with the other half, and pull any seeds that don't shake free from the pomegranate.
Take the cauliflower and kale out of the oven and add them to the bowl. Stir in ½ tbsp olive oil. Taste the salad and add a pinch more salt, pepper or cumin if you think it needs it. Divide the tabbouleh between 2 warm plates and serve.