Tangy Meatloaf Burgers

Name: Tangy Meatloaf Burgers
Ingredients: 1 small onion (1/2 sliced into rings, 1/2 diced); 1 pound meatloaf mix (ground pork, beef and veal) or ground turkey; 1/4 cup fresh parsley, chopped; 1/2 cup breadcrumbs (preferably panko); 1 large egg; 1 teaspoon sweet or smoked paprika; 1/3 cup ketchup; 1/3 cup duck sauce; Kosher salt and freshly ground pepper; 1 tablespoon extra-virgin olive oil; 4 potato buns or other rolls, split; Lettuce, sliced tomato and pickle slices, for topping; Sweet potato chips, for serving (optional)