Peel and finely slice the onion. Peel and grate the carrots. Grate the beetroot. Mix together the yoghurt with a few dashes of olive oil and add the juice of the lemon with a big pinch of salt. Mix the dressing thoroughly and season to taste. Combine with the veg.

Put the buns on to toast lightly. Slice the turkey. Spread the buns with mustard, then pile up the buns with turkey, green leaves and slaw.