Rinse the chicken livers under plenty of cold water in a colander.
Use several sheets of kitchen paper and place the chicken livers in an even layer. Add a few pieces on top and leave for a few minutes.
Cut the livers into even sized pieces about 4 or 5 centimetres.
Slice the tomatoes across the middle.
Roughly chop the walnuts so that there are still some larger pieces.
Mix together the oils and vinegar and season to taste.
Season the chicken livers with the salt and pepper.
Heat the butter in a frying pan over a medium heat.
Add the chicken livers in a single layer and spread out well.
Cook for 2 minutes then turn over for a further 2 minutes. Turn off the heat. The livers will be slightly pink in the middle.
Divide the salad leaves between 4 dinner plates.
Arrange the pan fried chicken livers on top.
Add the sliced tomatoes and scatter over the walnuts.
Shake the dressing and drizzle over just before serving warm.