As Steak ‘n Shake closes restaurants across the country, the founder of its San Antonio-based parent company has reported “dismal” financial performance last year due to significant losses from the burger chain. The holding company, Biglari Holdings, Inc. (NYSE: BH), acquired Southern Oil of Louisiana, Inc. in September for $51.5 million and is waiting on regulatory approval to acquire Arkansas-based Southern Pioneer Property & Casualty Insurance Co. in response to Steak ‘n Shake’s decline.…