Prep your pan: Lightly grease a 9x13-inch baking dish.
Preheat the oven to 375°F (190°C) if baking right away.
Cook the potatoes: If using fresh potatoes, dice into small cubes. Heat 1 tablespoon oil in a large skillet over medium heat. Add potatoes and a pinch of salt.
Cook, stirring occasionally, until golden and tender, about 10–12 minutes. If using frozen hash browns, cook until crisp and browned, 7–8 minutes. Transfer to a bowl.
Cook the meat: In the same skillet, cook sausage or chopped bacon until browned and cooked through.
Drain excess fat if needed. Add to the potato bowl.
Sauté the veg: Add another teaspoon of oil to the skillet. Sauté diced onion and bell pepper with a pinch of salt until soft and lightly browned, 5–6 minutes.
Stir in minced garlic, cumin, and chili powder for 30 seconds, until fragrant. Add to the bowl with potatoes and meat. Toss to combine.
Scramble the eggs: Whisk eggs with milk, 1/2 teaspoon salt, and a few grinds of pepper.
Melt 1 tablespoon butter in the skillet over medium-low heat. Pour in eggs and gently scramble until just set and still soft; they’ll cook more in the oven. Remove from heat.
Warm the tortillas: Briefly warm tortillas so they’re pliable.
Wrap in a damp paper towel and microwave 30–45 seconds, or toast quickly in a dry skillet.
Assemble the filling: In a large bowl, combine the potato-meat-veg mixture with the soft-scrambled eggs. Stir in 1 cup of shredded cheese. Taste and adjust salt and pepper.
The filling should be well seasoned.
Layer the sauce: Spread 1/2 to 3/4 cup red enchilada sauce across the bottom of the baking dish to lightly coat.
Fill and roll: Working one at a time, spoon about 1/3 to 1/2 cup of filling down the center of a tortilla. Roll snugly and place seam-side down in the dish. Repeat with remaining tortillas and filling.
Sauce and cheese: Pour the remaining red sauce evenly over the enchiladas.
You want them coated but not drowning. Sprinkle the top with the remaining 1 cup cheese.
Bake: Cover loosely with foil and bake for 15 minutes. Remove foil and bake another 10–12 minutes, until the cheese is melted and the sauce is bubbling around the edges.
Finish and serve: Let rest 5 minutes.
Top with chopped cilantro and green onions if you like. Serve with sour cream, hot sauce, and sliced avocado.