In a deep frying pan, pour in about ¼ inch of oil and add a pinch of salt. When the oil gets hot, pour in the potatoes and cover. Stir about every 5 minutes, replacing the lid and adjusting the temperature to keep the potatoes from scorching. When the potatoes are tender, add the green beans and cook until the beans are hot. Turn off the frying pan but keep the lid on.
In a medium-size pot, combine the sour cream, sage, basil, and salt and pepper to taste. Add just enough milk kefir to make it saucy, not thick. Cook just until it is warm, stirring constantly to keep it from scorching.
Drain the potatoes and green beans and place them in a glass serving dish. Pour the sauce over them or serve it on the side with a little ladle. Garnish with a sprig of fresh sage.
Cook the potatoes as directed but don’t add the green beans. Drain the potatoes and chill 4 to 5 hours. Add the green beans, cold. (Or use fermented green beans!)
Make sauce as directed but chill it and toss it with the cold potatoes and green beans. Serve cold.