Place the mango cubes, pineapple, and lime zest in the bowl of the blender.
Insert the blender (if using an immersion blender) or place the cover on top and blend on high speed until the mixture is smooth.
Add the kefir and lime juice on top of the fruit. Sprinkle the collagen powder and drizzle the honey or agave on top. Cover and puree on high speed until the mixture is smooth.
Pour it into 2 cups and enjoy. Or cover the mixture with a tight lid and store it in the refrigerator overnight.