Make cold foam with milk or whip the fluid from a can of unsalted chickpeas. To make cold foam, froth cold high fat milk with a hand frother. To make aquafaba foam, capture the liquid from a chilled unsalted chickpea can and whip with a hand frother or blender - it will take longer to produce foam with the aquafaba than with the milk.
Either way, flavor it by whipping in a teaspoon or two of pineapple juice or orange juice.
Make smoothie
Add all ingredients to the blender except for the frothed liquid and process until smooth.
2 cups mango, frozen, 1 cup pineapple, frozen, ½ cup milk, 2 teaspoon lemon juice
Pour the smoothie into a glass, spoon on the frothed top, and drink immediately.
¼ cup cold foam
Storage
Store smoothie without the foam in a covered jar for no longer than 24 hours. Or freeze in an ice cube tray to blend again when convenient.
Notes
Swap the pineapple for any other frozen fruit of a lighter color, such as frozen pears (not peeled), even a frozen banana, although paired with mango might produce a too-sweet smoothie.