For the salad, boil the Chantenay carrots for 5-7 minutes, until tender. Drain and set aside.
Heat one tablespoon of the oil in a frying pan and stir fry the spinach leaves for 1-2 minutes, until wilted. Season, to taste, with salt and freshly ground black pepper.
Heat the butter in another pan and fry the leeks for 6-8 minutes, until tender and slightly browned. Remove from the pan and set aside on a plate.
Heat the remaining tablespoon of oil in the same pan and fry the slices of sweet potato with the sugar and orange juice for about five minutes, until they are tender and caramelised.
For the dressing, place all the dressing ingredients, except the chervil, into a bowl and whisk well to combine.
To serve, place the wilted spinach on a serving plate and arrange the carrots, leeks and sweet potato on top. Top with the Arbroath smokie flakes and drizzle over the lemon dressing. Garnish with the chervil.