Preheat your oven to 200°C/Fan 180°C/Gas 6. Trim and scrub the beetroot and potatoes and chop them into bite-sized chunks. Trim and scrub the carrots and slice them into thick batons. Peel the red onions and slice them into thick wedges.
Tumble the veg onto a large baking tray, making sure the veg are spread out in a single layer. Use a second baking tray if you need to. Drizzle over 3 tbsp olive oil and season with a good pinch of salt and pepper. Toss to coat the veg. Wrap the garlic cloves in a parcel of foil and pop that on to the tray, then slide the tray into the oven for 45 mins, taking the garlic out after 30 mins.
While the veg roast, drain and rinse the chickpeas. Pop them in a bowl and drizzle over 1 tbsp olive oil. Add 1 tsp each ground coriander and caraway seeds, and 2 tsp fennel seeds with a good pinch of salt and pepper. Toss to coat the chickpeas.
Finely chop the mint leaves and add them to a small bowl. Zest and juice in the lemon. Pour in 2 tbsp olive oil and 1 tbsp cold water. Add a good pinch of salt and pepper and set aside.
Pull the soft kale leaves off their cores and roughly chop them, discarding the cores.
After 45 mins, remove the baking tray from the oven. Tip the chickpeas and kale onto the tray and toss together. Slide back into the oven for 15 mins.
Squeeze the roast garlic flesh from its papery skin, into the bowl with the lemon and mint dressing. Whisk together.
Remove the veg from the oven and divide it between 6 warm plates. Drizzle the garlicky mint dressing over the top of each plate to serve.