For the past few months Sonic had offered their "Signature Slinger" burger whose patty was a 60% beef and 40% mushroom blend. My wife and I adored it, but sadly

For the past few months Sonic had offered their "Signature Slinger" burger whose patty was a 60% beef and 40% mushroom blend. My wife and I adored it, but sadly they pulled it from the menu just recently.