Coarse salt and freshly ground black pepper
3 tbsp olive oil
some spices (e.g. paprika, garlic powder, chili powder)
Heat the oven to 425F. Cut the cauliflower into medium-sized florets, rinse and let some of the water remain clinging to the florets. Put them in a bowl, squeeze over the juice from the lemon. Toss with olive oil and sprinkle with salt, pepper, and spices. Place florets on baking sheet, along with cut-up segments of the lemon, and bake for 25-30 minutes, turning once. Serve immediately.
I adapted this from a recipe in the Guardian - they called for two lemons, which I think would have been way too much, it was already very lemony with just one, but if you had a really big head of cauliflower maybe two would be okay? Maybe English lemons are smaller? Dunno. It also called for paprika, which I didn't have on hand, so I used some garlic powder and a sprinkling of 'cajun spice' which is mostly just dried chilies, and it was yummy. I could have eaten a whole lot more of this, it gets all nicely caramelized around the edges. The recipe says it can also be done on the bbq, for those who have one :)