In a large pot, add the halved potatoes and the salt and garlic, and cover with cool water by at least 1 inch. Bring to a boil, lower to a simmer, and cook for 12-15 minutes, until fork-tender.
Drain the potatoes, and add back to the pot. Add the scallion, kale, butter, and kefir and mash together until the butter melts and you have a smooth mixture. Season to taste with salt and pepper.
To serve, transfer the mix to a serving bowl, make a well in the center, and melt a bit more butter in the well. Enjoy!
