Place the cauliflower on a sheet pan and toss with olive oil. Roast for 20 to 30 minutes, until it starts to brown and becomes soft. Turn it occasionally to brown evenly.
When the cauliflower is almost done add the whole cherry tomatoes and olives to the sheet pan and continue roasting until the tomatoes are just starting to burst about 5 more minutes.
Season with salt and lemon dressing Finish by adding the arugula and stirring just to wilt.
Giangi's Kitchen provides nutritional information, but these figures should be considered estimates, as a registered dietician does not calculate them.