Add the celery, apple, beets, and spinach to a blender, and blend until smooth.
2. Step
Using a mesh strainer, strain the juice over a large liquid measuring cup to remove the pulp. Use a spoon to help stir the pulp and press out the liquid. Reserve the pulp to make pulp muffins.
3. Step
Chill the juice for at least 30 minutes (and keep up to 3 days).
