Preheat the oven to 180'C.
Toast the walnuts in a dry frying pan or roasting tray in the oven for about 8 minutes. Allow to cool and break into small pieces. Remove the leaves from the Romaine lettuces, wash in cold water, spin in a salad spinner and cut into large pieces. Wash and then cut the apples into wedges and keep in cold water with a squeeze of lemon juice to stop them discolouring. Pick and chop the parsley.
Cut the fennel in half lengthways, remove the tough core at the base and slice finely on a mandolin. Wilt the fennel by lightly seasoning with salt. Place in a colander to allow the water to drain off.
Make your vinaigrette by whisking together the cider vinegar, mustard and the two oils and season with salt.
Remove the apples from the water and pat dry with kitchen paper. Place the apples in a large bowl with the lettuce and fennel. Dress with the vinaigrette and season with salt and pepper make sure that the leaves and apples are nicely coated with your vinaigrette. Add the walnuts and chopped parsley. Arrange in a bowl and serve immediately.
«Baby gem lettuce is an ideal replacement for Romain lettuce. Separate the leaves and do not discard the heart of the lettuce. This is the sweetest part!»