Orange, red onion and beetroot salad

A Hugh F-W recipe from the Guardian. A quick and perky starter for a winter lunch or supper. Serves four.

3 beetroot, roasted, peeled and thinly sliced
2 oranges, peeled with a knife to get rid of all traces of skin and pith, then thinly sliced (hold the fruit over a bowl, to catch any juice, and squeeze any juice you can extract from the skin and add this to the dressing)
1 red onion, peeled and thinly sliced

For the vinaigrette
1 tsp white-wine vinegar
1 tsp Dijon mustard
3 tbsp olive oil
Salt and pepper

Arrange the beetroot, orange and onion on four plates (or on one large platter). Whisk together the reserved orange juice, vinegar and mustard, then whisk in the oil. Season to taste, and trickle the dressing all over the salad.