Heat oil in a heavy large skillet over medium-high heat. Add meatballs and cook until brown, about 8 minutes. Using tongs, transfer meatballs to a bowl. Add flour to skillet and cook 1 minute over low heat, scraping up browned bits from bottom of skillet. Stir in broth, milk, sour cream, meatball seasoning, chives and seasoning salt, to taste, using a whisk.
Return meatballs to skillet. Simmer until liquid thickens enough to coat meatballs, about 5 minutes. Remove skillet from heat. Spoon sauce on top of meatballs and serve immediately.