Heat a large, nonstick skillet over medium-high heat. Add the sausage and break it up into small pieces with a wooden spoon. Cook it for about 5 minutes, until it’s browned and no pink remains. Using a slotted spoon, remove the sausage and place it on a paper-towel lined plate, leaving the drippings in the skillet.

To the same skillet, add the hash browns and spread them in an even layer. Cook, without stirring, over medium-high heat for about 2 minutes, until they are browned on bottom. Stir and cook them for about 2 more minutes, until they are evenly browned all over. Remove the skillet from the heat and place the hashbrowns on a plate.

In a medium bowl, whisk together the eggs, salt, and pepper. To the same skillet, add the butter and melt it over medium heat. Pour in the eggs and stir and scramble with a rubber spatula for 2 to 3 minutes, until just cooked through. Place the eggs on a plate.

Wrap the tortillas in a damp paper towel and microwave them for 30 seconds until soft. Place them in a single layer, side-by-side, on a large work surface. Divide the sausage, hash browns, eggs, cheese, avocado, and cilantro evenly among the tortillas. Fold in the sides of the tortillas over the filling and roll, tucking in the edges as you roll. Hold the burritos seam-side down so that they don’t open, until you serve them.

If you would like to brown the outside of the burritos, heat a nonstick skillet over medium heat. Add the burritos seam-side down. Cook for about 2 minutes, until the bottoms are golden brown. Flip and cook for another 2 minutes, until the other sides are golden brown. Serve the burritos warm with sour cream and salsa.