Roast the cashews in an oven tray for 5 minutes or until golden brown. Set aside.
Coarsely chop the sweet potato, skin on, toss in olive oil and salt, and bake for 40 minutes or until golden brown and starting to caramelise. Set aside to cool.
Blitz sweet potato in a food processor until smooth. Add half of the cashews, 3 heaped tablespoons Greek yoghurt, 3 teaspoons harissa, ⅛ cup extra virgin olive oil, 2 teaspoon salt and 2 teaspoon red wine vinegar. Blitz again until smooth and combined. Season further to taste.
Crush remaining cashews in your hands and put a few aside to garnish. Along with ⅛ cup extra virgin olive oil, fold the remaining cashews through the dip.
Sprinkle with harissa and cashews, and drizzle with extra virgin olive oil to serve.