Chorizo and Potato Breakfast Tacos

vegetable oil

ground Mexican chorizo

russet potatoes, peeled and cubed into 1/2 inch cubes

medium yellow onion, diced

serrano pepper, thinly sliced

green onions, thinly sliced

kosher salt and black pepper,

large eggs, lightly beaten

unsalted butter

soft taco sized corn or flour tortillas

chopped fresh cilantro, (for garnish)

salsa, (for garnish)

sour cream, (for garnish)

shredded cheese, (for garnish)