Fruit Salad with Celery

Peel the orange, making sure to remove all of the bitter white pith. Remove the whole fruit segments, collecting any juice created in a bowl. Peel and quarter the apple. Remove the core, finely dice, then mix with a little orange juice. Rinse, trim, and cut into narrow oblique slices. Peel the kiwi, cut into quarters, and thinly slice. 

Coarsely chop the walnuts, and toast in a dry pan. Remove the walnuts from the pan and set aside. Mix the yogurt with the sour cream, oil, and 2 tablespoons of orange juice. Mix until combined, then season to taste with salt and pepper. Place the yogurt in a small bowl. Top the yogurt with the celery, half of the orange segments, the apple, kiwi, and walnuts.