Iin a large bowl, combine all the meatball ingredients except for oil, and mix until evenly combined. Heat 1 Tbsp of the oil in a 12-inch, skillet over medium heat. Scoop meatball mixture into balls, about 1-2 inches in diameter, and add in a single layer to the hot oil. Brown on all sides, no need to cook all the way through yet as they'll finish cooking later; remove to a paper towel-lined plate, leaving as much oil in the pan as possible, and repeat with remaining meatballs, adding a bit more oil to the skillet if needed.

Return skillet to medium heat and add 1 Tbsp butter and 1 Tbsp oil for the sauce, cooking until melted. Stir in the flour and cook, stirring constantly, for 1-2 minutes to brown the flour mixture and cook out the flour taste. The mixture will be a bit crumbly. Slowly add broth, 1/2 cup at a time, whisking quickly to remove any lumps. 

Let each addition of broth cook until thick and smooth before adding the next 1/2 cup. After 2 cups, pour in the rest and whisk until combined. Stir in brown sugar and bring the sauce to a low simmer. Add the meatballs back to the skillet into a single layer and cook 10 or so until cooked through, turning them once or twice to coat with sauce.

Turn off  heat, stir in sour cream, whisking it in after sauce no longer simmers. Garnish with fresh parsley and serve over hot, cooked egg noodles, potatoes or rice.