Heat 2 tablespoons olive oil in a large saucepan over medium heat until shimmering. Add leeks, onions, garlic, and ginger, and cook, stirring frequently, until vegetables are softened but not browned, about 5 minutes. Add cumin, coriander, and harissa paste and cook, stirring constantly, until fragrant, about 1 minute. Add carrots and stir to coat in spice mixture. Add broth (see note), season with a pinch of salt, bring to a boil, reduce to a bare simmer and cook, stirring occasionally, until carrots are completely tender, about 20 minutes.

Meanwhile, heat 2 tablespoons olive oil in a small skillet over medium heat until shimmering. Add pine nuts, reduce heat to low, and cook, tossing and stirring constantly, until fragrant and nutty brown, about 10 minute. Transfer to a bowl. Let cool for a few moments, then stir in parsley, lemon zest, and a pinch of salt.

When carrots are tender, transfer half of soup to a blender. Start blender on lowest speed and slowly increase speed to high. With blender running, slowly drizzle in remaining 2 tablespoons extra-virgin olive oil. Transfer soup to a clean pot, pressing it through a fine mesh strainer or chinois if desired. Repeat with remaining soup and 2 more tablespoons olive oil. When all the soup is puréed, season to taste with salt and whisk in lemon juice.

Serve soup immediately, topped with pine nut and parsley mixture.