Heat oil over medium to medium-high heat in cast iron skillet. Brown chicken thighs about 4 minutes on each side and remove from pan.
Add tablespoon olive oil to pan and saute onions and mushrooms until browned, about 5 minutes.
Add wine to pan and bring to boil reducing by half.
Mix together stock and flour and add to pan. Return chicken to pan and bring back to boil. Cook an additional 5 minutes until sauce is thickened and chicken is cooked through.