Cauliflower with Dill Sauce

Oh dear Lord, this is truly amazing.  I was so glad we got a head of cauliflower at the Farmer's Market--so much zucchini, but really, we need some variety to hold us over until it is all cucumbers, tomatoes, and corn, a season that characterizes the next couple of months in the Midwest.

1 large head of cauliflower (about 2 pounds)
10 cherry tomatoes, halved
handful of arugula
1 tablespoon dill, chopped
1 tablespoon whole grain mustard
2 tablespoons capers, roughly chopped
2 cloves garlic, minced
2 tablespoons cider vinegar
120 ml (1/2 cup) olive oil, plus more for drizzling
sea salt
pepper

Turn on oven to broil.
1. Make the dressing. In a jam jar, mix the capers, mustard, garlic and vinegar. Let sit for 15 minutes to a half-hour. Add the oil, shake it up, and add salt and pepper. Set this aside while you cook the cauliflower.
2. Put the cauliflower florets on a parchment-lined cookie sheet and drizzle with a bit of olive oil and sprinkle on some sea salt and fresh pepper, too. Slide into the oven until it begins to brown, about 15 minutes. Take out the pan and turn the cauliflower over, so the other side gets brown, too. This will take about 10 more minutes. When the cauliflower is nice and roasted, remove from oven and set aside.
3. In a large bowl, put the cauliflower, tomatoes, arugula and dill. Add the dressing and gently toss.
It can be eaten warm or at room temperature (or as leftovers, cold, the next day.