Preheat the oven to 400ºF (200ºC). Lay the bacon out in a single layer on an aluminum foil-lined baking sheet. Bake the bacon until crispy and golden brown, about 15 minutes. Remove to a paper towel-lined plate to cool then crumble the bacon.
Heat a small sauté pan over medium heat. Add the breakfast sausage and cook, stirring occasionally, until browned and cooked through, about 8 minutes. Remove and set aside, covered in a bowl until ready to use.
Add the diced potatoes to a bowl of cool water and vinegar. Drain and pat the potatoes dry with paper towels. In a large non-stick skillet over medium heat add the oil and heat through.
Add the onions and potatoes and cook, stirring occasionally, until the potatoes are golden brown and crispy on all sides, about 15 minutes. Season with salt and pepper and remove to a medium serving bowl.
Preheat the oven to 200ºF (93ºC) and warm the tortillas on a baking sheet for about 10 minutes.
In a large mixing bowl, whisk together the eggs and heavy cream until the eggs fall in ribbons. Heat a large skillet over low heat, add the butter and allow to melt. Add the eggs and let sit for a second and season with kosher salt. Use a rubber spatula to move the eggs from side to side while also scraping the sides constantly.
It will take some patience but after about 10 minutes the eggs will begin to form curdles. Continue to cook, stirring constantly, until the eggs are just set, about 5 minutes. Stir in the cheese then remove the eggs from the pan to a medium serving bowl.
Arrange all of the breakfast taco bar ingredients on a table with serving spoons and let people make their own tacos. If you choose to serve them already assembled then spoon some of the eggs onto a warmed tortilla and top with desired toppings, sausage, bacon, green chilies, potatoes, and cilantro.