Heat your oven to 200°C/Fan 180°C/Gas 6. Trim and slice your carrots in half lengthways. Trim the beetroot. Cut into 1 cm thick rounds. Peel the onion and cut into thick wedges.
Tumble the veg onto a baking tray. Scatter over 1 tbsp cumin seeds. Drizzle over 1 tsp oil. Season. Put 1 garlic clove (unpeeled) on the tray. Slide into the oven and roast for 25 mins till the veg is soft and slightly charred.
Meanwhile, chop your cauli into florets. Blitz them in a food processor till they have a rice-like texture. If you don’t have a food processor, you can grate it. Peel and grate the remaining garlic clove. Zest and juice the lime.
Pour the lime juice into a pan. Add 2 tbsp cold water. Scrape in the grated garlic. Set the pan over a medium heat. Bring to a simmer, then add the cauliflower rice. Fold the cauliflower through the lime juice. Cook for 5 mins to warm through.
When the carrots and beetroot have roasted for 25 mins, remove the garlic clove. Scatter in 1 tbsp pumpkin seeds and roast the veg for a further 5 mins.
Squeeze the roasted garlic from its skin using the back of a knife. Finely chop most of the coriander leaves and stalks, saving a few leaves for garnishing. Tip them into a bowl. Add 2 tbsp tahini and 4 tbsp cold water. Season well and mix.
Spoon the limey cauliflower rice onto two plates. Top with the roasted veg and seeds. Drizzle over the green coriander tahini sauce. Scatter over the lime zest and serve.