Halve the avocado and remove the seeds. Dice the pulp, and set some aside for garnish. Drizzle the reserved avocado with a few drops of lemon juice. Puree the remaining avocado with the white wine and the lemon juice in the blender.
Peel the garlic. Bring the broth to a boil, then pass the garlic through a press into the broth. Remove from the heat, and gradually whisk in the avocado puree.
Mix in the creme fraiche, then season to taste with salt and pepper. Chill for at least 1/2 hour in the refrigerator. Cut the bread into cubes. Heat the oil in a pan, and toast the bread. Garnish the gazpacho with the reserved avocado and the croutons, then serve.