Preheat the oven to 180°C (350°F). Line a large baking tray with baking paper. Cut the cauliflower in half or thirds and then trim the outside sections to create 2 or 3 thick steaks.
Heat the oil in a large frying pan over medium heat. Cook the cauliflower for about 10 minutes each side, until caramelised. Transfer the cauliflower to the baking tray. Season with salt and pepper and top with thyme and lemon slices. Bake for 15–20 minutes, until soft and golden.
To make the beetroot hummus, place the chickpeas, beetroot, olive oil, tahini, garlic, lemon zest and juice into a blender or food processor and blend until combined and smooth. Season with salt and pepper to taste.
Remove the thyme and lemon. Serve cauliflower steaks and beetroot hummus with a side of salad and poached egg, if desired.