- Arrange the salad leaves on serving plates.
- Heat the oil in a non-stick frying pan, add the onion and cook for 5 minutes or until softened.
- Add the chicken livers, tarragon and mustard and cook for 3-5 minutes, stirring, until tender.
- Place on top of the salad leaves.
- Add the vinegar, salt and pepper to the pan and heat, stirring all the time, until all the sediment has been lifted from the pan.
- Pour over the chicken livers and serve warm.