In the bottom of a blender, add water, frozen pineapple chunks, avocado, spinach, and ice cubes (in that order). Blend until smooth.
Water: Or substitute your favorite milk or non-dairy beverage for the water. I love almond milk in mine.
Avocado: Looking for more protein? Use 1 cup Greek yogurt in place of the avocado.
Spinach: Or substitute fresh kale, Swiss chard, or escarole.
Yield: This recipe makes 2 servings, 8 ounces each.
Storage: Store any leftover smoothie covered in the refrigerator for up to 8 hours (the avocado may oxidize and change the color; to prevent this, cover the top of the smoothie with a thin layer of water, then stir to recombine before enjoying).
Customize: Change this smoothie as you see fit, keeping the proportions of liquids and solids. Use a different frozen fruit, change your greens to kale or Swiss chard, or add a spoonful of ground flax, protein powder, or hemp seeds.
High-powered blender: For the smoothest results, use a high-powered blender. The two major players are Blendtec and Vitamix, and both are great (I have a Blendtec at home but used a Vitamix in culinary school).