To prepare the eggs: Crack the eggs into a medium bowl and whisk them with a fork until the mixture is pale yellow. Stir in the beans and season the salt and hot sauce. To cook the eggs: Melt the butter in a medium-sized skillet (either well-seasoned cast iron or nonstick) over medium heat. Pour in the egg mixture and cook, stirring often, until the eggs are just set, about 2 to 4 minutes. Stir in the cheese and transfer the mixture to a bowl. Then stir in the cilantro and green onion (if you’re serving the burritos right away, reserve a small amount of each for garnish). To make sure the tortillas are nice and pliable, quickly run each tortilla under running water (trust me). Warm the tortillas briefly in the microwave (about 10 to 20 seconds) or in a skillet. Working with one tortilla at a time, spread about 1/3 cup hash browns on a tortilla about one-third from the edge. Drizzle 1 tablespoon salsa on top of the hash browns. Top with about 1/3 cup scrambled eggs. (You can eyeball the amounts of hash browns and scrambled eggs; just try to divide them evenly between the tortillas.) Roll up the burrito by first folding the tortilla over from the bottom to partially cover the contents, then fold in the two sides. Finish rolling and put the burrito seam side down on a plate. Repeat with the remaining burritos. If you’re serving the burritos right away: You can halve the burritos like I did, or serve them whole. Warm some extra salsa in the microwave or on the stove, then pour it over the burritos. Top with diced avocado (if using) and the reserved cilantro and green onion. Serve immediately, with a knife and a fork. If you’re freezing the burritos for later: Let the burritos cool to room temperature, then wrap each burrito in plastic wrap. Transfer the wrapped burritos to a freezer-safe bag and squeeze out the air before sealing. Store the burritos in the freezer. For best flavor, consume your burritos within 3 to 6 months. To defrost frozen burritos, unwrap the plastic wrap and then wrap the burrito in a damp paper towel. Microwave about 2 to 3 minutes, until warmed throughout. I like to serve mine with some extra salsa.