Preheat oven to 450

Cut cauliflower into florets and place in a single layer on large rimmed baking sheet. Use 2 trays, if needed, so the cauliflower fits in one layer.

Drizzle cauliflower with olive oil and mix well, so oil is evenly distributed. Mix paprika with salt and pepper, sprinkle spice mixture over the cauliflower, and mix thoroughly. It's easier (and messier) to do this with your hands, but you could also use a large pair of tongs. Place cut sides down, where you can. The underside will crisp up when roasted.

Roast for 15-20 minutes, until crisp on the edges and tender inside.

Meanwhile, make dressing. In a small bowl, whisk together vinegar and mustard. Then add in spices and whisk. Cut shallot into small dice and whisk into mixture. Last, add in the oil and continue to whisk, until fully incorporated. Alternately, place all ingredients into a small jar with right fitting lid and shake vigorously until mixture is emulsified.

Place arugula in bowl and toss with 2 Tablespoons dressing. Arrange on a serving platter. No need to wash the bowl. Next add the roasted cauliflower to the bowl and toss with 1-2 Tablespoons dressing. Add cauliflower to the platter with arugula.