Preheat your oven to 200°C (390°F).
On a baking tray, toss the cubed pumpkin and cauliflower florets with 2 tablespoons of olive oil, salt, and pepper. Roast for 25 minutes, or until golden and tender.
While the vegetables are roasting, prepare the harissa dressing by mixing the remaining olive oil with the harissa paste in a mixing bowl. Adjust the seasoning to taste.
In a large bowl, combine the arugula, chickpeas, roasted pumpkin, and cauliflower. Stirr gently to mix.
Drizzle the harissa dressing over the salad and toss gently to coat.
Serve topped with fresh dill, a dollop of yogurt on the side, and optional toppings like crumbled feta and toasted pumpkin seeds.