Place the chicken thighs in between a large piece of clear plastic add a little water and beat out until nice and thin.
Repeat with the 3 others.
Coat each one in a little flour, then egg and seasoned breadcrumbs, pat well.
Fry each one in oil and unsalted butter until cooked through and nicely browned.
To make garnish, add red wine vinegar to sliced red onions and leave for 20 minutes, stirring occasionally.
Serve with a potato dish.