Preheat the grill to high.
Place the cauliflower florets in a bowl and toss them with the olive oil, garlic powder and a big pinch of salt and pepper. Toss until all the florets are covered then transfer to a grill pan.
Place the pan directly on the grill and grill for 15 to 20 minutes, tossing the cauliflower every 5 minutes. You may need to grill slightly less or more based on the size of your florets. Make sure they are golden, toasty and tender!
Place the ears of corn directly on the grill too. Just like the cauliflower, turn it every 4 to 5 minutes, until the corn is charred and golden.
While grilling, place the arugula in a large bowl. Toss with a big pinch of salt and pepper. Make the vinaigrette too.
When the cauliflower and corn is finished, let it cool slightly. Slice the corn off the cob. Add the corn and cauliflower to the arugula and toss. Drizzle with the dressing all over - as much as you wish, but I start with 3 to 4 tablespoons and go from there, tossing the salad as I go.
Sprinkle with the pistachios. Season with more salt and pepper if needed, then serve!