In a medium bowl, whisk flours, 1/2 tsp. sesame oil and 1/3 cup boiling water. Knead on a work surface until ball forms, 4 to 5 turns. Cover; let rest 20 minutes. On a floured surface, roll out to 1/4-inch-thick round. Brush with 1/2 tsp. sesame oil; top with scallions. Roll up; cut crosswise into 4 pieces. Roll each to 1/4 inch. Coat pancakes with spray; cook in a large nonstick skillet over medium-high until golden, 3 minutes per side; slice. Serve with soy sauce.