How to Make It
Stir together mashed potatoes, carrots, flour, eggs, scallions, salt, and pepper in a medium bowl until combined. Form into 12 pancakes (heaping 1/4 cup each). Chill 10 minutes.
Heat olive oil in a large skillet over medium-high. Working in batches, fry pancakes until golden brown, 2 to 3 minutes per side.
Whisk together soy sauce, rice vinegar, sesame oil, and seeds in a small bowl. Serve pancakes warm with sesame sauce.