Cut the rind off the toast. Dice bread slices. Melt 1 tablespoon of fat in a pan. Roast the bread cubes golden brown while turning, season with salt. Wash orange hot, rub dry, peel off zests with a pestle ripper.
Cut the orange in half and squeeze. Peel and finely dice the onion. Melt 2 tablespoons of fat in a pot. Sauté onion in it until transparent. Dust the onion with flour and continue to fry for about 1 minute while stirring.
Add white wine, stock and milk while stirring, bring to the boil, simmer for 1 minute. Wash the rocket, dab dry, clean, put 4 nice leaves aside for garnishing. Cut remaining rocket into strips.
Add the rocket and orange juice to the soup and puree finely with a hand blender. Season to taste with cayenne pepper, nutmeg and salt. Stir in 100 g sour cream. Arrange the soup in plates. Garnish with a rocket leaf, orange zest and the remaining sour cream.