Pierce 4 sweet potatoes with a fork; microwave 8 minutes. Scoop the flesh into a bowl, then mash. Brown 3 tablespoons butter in a skillet, then add 8 sage leaves and fry until crisp; transfer to a plate. Cook 4 chopped scallions with salt and pepper in the browned butter. Drizzle over the sweet potatoes; top with the sage.
Photograph by Antonis Achilleos