Pop in a baking tray and dollop with the harissa paste. Mix around until each chunk is coated.
Drizzle with oil and mix again to ensure the oil is evenly spread around.
Roast the squash for 20-30 minutes or until it has softened and started to caramelise around the edges.
Blend with the boiling water for 30-60 seconds until it is smooth. Use a little less water if you prefer a thicker soup, or a little more if you like it thinner.
Toast the sunflower seeds in a hot, dry frying pan until lightly browned and scatter over each bowl of soup for a little bit of tasty texture.