Put potatoes in a large pot and cover with cold water. Bring to a boil.
When water begins to boil, add eggs to the pot. Boil for 12-14 min, or until potatoes are tender. (Test with a fork.) Remove eggs; crack the eggshells and set eggs in a bowl of cold water.
Drain potatoes in colander and allow to cool.
Mix avocado and mayo in a large bowl using a potato masher or a fork.
Add scallions, garlic, salt, and pepper.
Peel and chop eggs, and add them to the dressing.
Add cooled potatoes, tossing all ingredient until potatoes are well-coated.