Heat the vegetable oil in a large skillet over medium-high heat. Add the frozen hash brown potatoes and cook for 8 to 10 minutes, stirring occasionally, until golden brown and tender.
Season the potatoes with ¼ teaspoon salt and ⅛ teaspoon black pepper.
Transfer the potatoes to a plate.
Add the breakfast sausage to the same skillet. Cook over medium heat for 5 to 7 minutes, breaking it into small pieces, until browned and fully cooked.
Transfer the sausage to a plate.
Add the onion, green bell pepper, and red bell pepper to the skillet. Cook for 3 to 4 minutes, stirring occasionally, until slightly softened.
In a medium mixing bowl, whisk the eggs, milk, remaining ¼ teaspoon salt, and remaining ⅛ teaspoon black pepper until blended.
Melt the butter in a medium skillet over medium-low heat.
Pour the egg mixture into the skillet and cook, stirring gently with a spatula, until the eggs are softly scrambled and just set.
Place the tortillas on a microwave-safe plate and microwave for 20 to 30 seconds until warm and flexible.
Divide the scrambled eggs evenly among the four tortillas.
Top each tortilla with equal portions of sausage, potatoes, onion, and bell peppers.
Sprinkle ¼ cup shredded cheddar cheese over the filling in each tortilla.
Fold the sides of each tortilla toward the center.
Roll each tortilla tightly around the filling.
Place the burritos seam-side down in the large skillet over medium heat. Cook for 1 to 2 minutes per side until lightly browned.
Serve warm with ketchup or hot sauce, if desired.
Notes
Tips and Tricks
Don't Overfill - These burritos have quite a bit of filling. Leave enough room around the edges so you can fold and roll them without tearing the tortillas.Drain the Sausage - If the sausage releases a lot of grease, drain the excess before filling the burritos. This helps prevent soggy tortillas.Keep the Eggs Soft - Remove the eggs from the heat as soon as they're set. They'll warm up again when you brown the assembled burritos.Cool Before Freezing - Let the cooked filling cool before wrapping burritos for the freezer. Trapped steam can make the tortillas soggy.
Storing and Reheating
Refrigerator - Store cooled burritos in an airtight container or wrap them individually. Refrigerate for up to 3 to 4 days.Freezer - Wrap cooled burritos individually in foil or freezer-safe wrap. Place them in a freezer bag and freeze for up to 2 months for best quality.Microwave - Remove any foil and wrap the burrito in a damp paper towel. Microwave a refrigerated burrito for 1 to 2 minutes or a frozen burrito for 3 to 5 minutes, turning halfway through. Heat until the center reaches 165°F.Oven - Wrap the burrito in foil and reheat at 350°F for approximately 15 to 20 minutes if refrigerated, or 30 to 40 minutes if frozen. Heat until the center reaches 165°F.