Combine flour, salt, and boiling water in a large bowl and stir to combine until a mass of dough forms. Transfer dough to a lightly floured surface and knead until smooth, slightly tacky ball forms, 3 to 4 minutes.
Transfer dough ball to a medium bowl and cover with a kitchen towel or plastic wrap. Let rest 30 minutes at room temperature, or up to overnight in the refrigerator.
In a small bowl, combine 2 tablespoons vegetable oil and sesame oil.
Once the dough has rested, separate into four equally sized balls. Return three to bowl and recover with kitchen towel or plastic wrap. Roll out the ball on a lightly floured surface as thinly as possible, 8-10 inches and brush with a thin layer of the oil mixture. Top with ¼ of the sliced scallions. Roll dough away from you into a tight, thin cylinder, like a jelly roll. Starting at one end, form into a coil, like a cinnamon roll. Using a rolling pin, roll out dough again to form a pancake about 8-10 inches. Repeat with the remaining dough.
Add ¼ cup vegetable oil to a skillet over medium-high heat until shimmering and gently add first pancake. Cook, undisturbed, until golden on one side. Flip and cook until golden on underside, about 2 to 3 minutes per side. Remove to paper-towel lined plate. Repeat with the remaining pancakes, adding more oil if necessary.
Cut the pancakes into quarters (triangles) and serve with dipping sauce.
Dipping Sauce:
Combine all ingredients and pour into a small serving bowl.