Chorizo Hash Browns

1 small onion, finely chopped 
3 scallions, finely chopped 
1 garlic clove, minced 
2 tablespoons extra-virgin olive oil, divided 
2 pound russet (baking) potatoes (about 3) 
1 1/2 to 2 ounces Spanish chorizo (cured spiced pork sausage), casing removed and sausage finely chopped (1/2 cup) 
1/4 cup chopped flat-leaf parsley 
1/8 teaspoon paprika 
1 tablespoon unsalted butter

Cook onions, scallions, and garlic in oil over medium heat until softened, 3 to 5 minutes. Coarsely grate potatoes and squeeze excess moisture from them. Mix with onion mixture and form patties. Heat butter and oil over medium heat and brown patties on both sides, 10 minutes. (Serve with Chipotle Sour Cream? Topped with chives or minced cilantro?)