1 Rinse the celery, emove any stringy fibers, and cut into small pieces. Halve the avocados and remove the seeds. Scoop out the pulp, then puree immediately with 1 teaspoon of lemon juice in a blender.
2 Rinse and quarter the apple. Remove the core, coarsely chop, then add to the blender with the celery, yogurt, and orange juice. Puree the mixture completely, then season to taste with salt and lemon juice.
3 Pour the smoothie into glasses. Garnish with celery leaves and a slice of avocado, if you'd like, and serve.