Preheat oven to 400 degrees Fahrenheit.
Cut the cauliflower into florets. Line a baking sheet with parchment paper and place the florets on top. Add the curry powder and cayenne pepper, then drizzle the florets with olive oil or melted coconut oil. Spread out the florets and make sure they are well-coated with spices and oil.
Roast in the oven until the cauliflower is golden brown, about 30 minutes. Remove from the oven and let cool slightly.
While the cauliflower is still warm, toss with arugula. Finish with lime juice, salt to taste and a sprinkle of toasted cashews.