Place the salad leaves in a bowl, add the dressing and toss lightly. Slice the ham into thin shreds. In another bowl, beat the eggs then stir in the ham and a little seasoning.
Melt the butter in a small frying pan, approximately 24cm in diameter, and tip in the omelette mixture. Using a fork, push the cooked mixture into the centre of the pan, tilting the pan so the uncooked eggs fill any gaps left behind. When the mixture starts to set, reduce the heat and cook gently for about 30 seconds until lightly set all over.
Meanwhile, warm the wrap under a preheated grill for 10-15 seconds on each side, or in the microwave on medium power for 10-15 seconds.
Slide the omelette onto the warmed wrap and arrange the salad on top. Tightly roll the wrap (see Cook's tip) then slice to serve. If adding to children's lunchboxes, leave to cool then wrap in clingfilm.