Heat vegetable oil in a large skillet over medium heat.
Add Chorizo sausage to the pan and cook, breaking up the sausage into small crumbles with a wooden spoon until cooked through. Drain off any excess fat leaving about 1 tablespoon in the pan.
Remove sausage from the pan and set aside. Add the diced onion and cubed potatoes to the pan.
Cook, stirring occasionally until the potatoes are fork tender and the onions are soft and beginning to brown.
Add the spices (salt, pepper, cumin, chili powder and garlic powder) to the pan and stir until the potatoes and onions are coated with the spices.
Return the cooked Chorizo sausage to the pan and stir to combine with the onions and potatoes and everything is heated through, about 2-3 minutes.
Top with a layer of shredded cheddar cheese.
Turn off the heat, cover the pan with a lid and let it sit, covered for about 5 minutes, to allow the cheddar cheese to melt.
Top each serving with a dollop of sour cream.