Broil the tortillas
Preheat the broiler to high and line two sheet pans with foil. Place the tortillas on the pans and sprinkle half of the cheese over each. Broil one pan at a time for approximately 20 seconds, just until the cheese begins to melt.
Prepare the refried beans
In a medium nonstick skillet, heat 1 tablespoon of oil over medium heat. Add the sliced scallions and ground cumin, cooking for about 1 minute until fragrant. Stir in the refried black beans and cook for another 2 minutes until thoroughly warmed. Divide the beans evenly across the tortillas, placing them in a line down the center of each.
Scramble the eggs
Wipe the skillet clean and return it to medium-low heat. Add the remaining tablespoon of oil and pour in the beaten eggs, seasoning lightly with salt. Stir occasionally and cook for about 3 minutes, until the eggs are set but still soft. Once done, distribute the eggs evenly across the tortillas on top of the beans. If desired, drizzle with hot sauce.
Assemble the burritos
Sprinkle the remaining cheese over the eggs, then add slices of avocado and fresh cilantro on top. To roll, fold one side of each tortilla over the filling, then tightly roll away from you, leaving the ends open. Serve immediately, or wrap each burrito in foil for storage. If preparing ahead of time, refrigerate for up to 24 hours. To reheat, place the burritos in a 400-degree oven or toaster oven for about 8 minutes, or until warm throughout.