Heat your oven to 200°C/Fan 180°C/Gas 6. Pop a large roasting tin in the oven to heat up.
Cut the cauliflower into 3cm chunks, keeping the smaller green leaves in tact (you can keep the larger, outer leaves for something else, like sauerkraut or a stir-fry). Give the chopped cauli a good wash. Halve, peel and slice your onion. Tug the kale leaves from their woody stems. Wash well and roughly chop. Pluck the tomatoes from their stems. Quarter the lemon.
Pile the veg, lemon quarters, fennel seeds, ground coriander and 1 tsp turmeric (keep the rest for later) into the warm roasting tin with 1 tbsp olive oil and a good pinch of salt and pepper. Give everything a good mix. Roast for 25 mins or till tender and a little crisp around the edges.
While the veg cooks, peel the ginger and chop into thin matchsticks. Thinly slice the chilli. Peel and thinly slice the garlic. Set a frying pan over high heat. Add 1 tbsp olive oil and the ginger, garlic and chilli with a pinch of salt. Lower heat slightly and fry till just golden. Spoon into a little dish.
Mix the remaining turmeric and any residual oil from the frying the ginger, chilli and garlic through the yogurt. Season with salt and pepper.
Once the veg is cooked, squeeze some of the roasted lemon wedges over the veg. Serve the veg piled up on warm plates with dollops of the turmeric yogurt and the crispy ginger, chilli, garlic scattered over the top.