Step 1: Make the Scallion Pancake Dough

In a large mixing bowl, combine the all-purpose flour and hot water. Mix with a wooden spoon or chopsticks until the dough comes together. Once cool enough to handle, knead the dough on a lightly floured surface for about 8-10 minutes, or until it becomes smooth and elastic. Cover the dough with a damp towel and let it rest for 30 minutes.

Step 2: Prepare the Beef Filling

In a medium bowl, combine soy sauce, hoisin sauce, oyster sauce (if using), sugar, sesame oil, garlic, and ginger. Add the thinly sliced beef to the marinade, ensuring every piece is evenly coated. Cover and let the beef marinate for at least 20 minutes (or up to 1 hour for deeper flavor).

Step 3: Roll Out the Scallion Pancakes

Divide the rested dough into 4 equal portions. Roll each portion into a ball. Working with one ball at a time, roll it out into a thin circle (about 8 inches in diameter). Brush the surface with sesame oil, sprinkle a pinch of salt, and scatter ¼ cup of chopped scallions evenly across the dough. Roll the dough into a tight log, then coil it into a spiral. Flatten the spiral with your palm and roll it out again into an 8-inch circle. Repeat with the remaining dough.

Step 4: Cook the Scallion Pancakes

Heat 1 tablespoon of vegetable oil in a nonstick skillet over medium heat. Cook each scallion pancake for 2-3 minutes on each side, or until golden brown and crispy. Remove from the skillet and keep warm under a kitchen towel. Repeat with the remaining pancakes.

Step 5: Cook the Beef

Heat 2 tablespoons of vegetable oil in a large skillet or wok over medium-high heat. Add the marinated beef and stir-fry for 3-5 minutes, or until the beef is cooked through and slightly caramelized. Remove from heat and set aside.

Step 6: Assemble the Beef Rolls

Place one scallion pancake on a flat surface. Spread a thin layer of hoisin sauce over the pancake, adding a drizzle of Sriracha if you prefer some heat. Add a few slices of cooked beef, a handful of julienned scallions, fresh cilantro leaves, and any additional toppings like pickled vegetables or cucumbers. Roll the pancake tightly around the filling, tucking in the edges as you go. Repeat with the remaining pancakes and filling.

Step 7: Serve and Enjoy

Cut each beef roll in half diagonally and serve warm. These rolls can be enjoyed as is or with a side of dipping sauce, such as soy sauce mixed with a touch of rice vinegar and sesame oil.