How to Make It
In a large bowl, toss the russet and sweet potatoes with the scallions, thyme, salt and pepper.
In a heavy 9- to 10-inch non-stick skillet, heat 1 tablespoon of the vegetable oil. Spread half of the potato mixture evenly in the pan and cook over moderately high heat until firm and browned on the bottom, about 5 minutes. Turn and cook until browned on the other side, 4 to 5 minutes longer. Transfer the potato pancake to a large baking sheet and keep warm in a low oven. Repeat with the remaining vegetable oil and potato mixture. Cut each pancake into 6 wedges and serve hot.