Cook 4 medium beetroot, peel and grate.
Peel and chop two large onions, fry until caramelized but still soft. Mix with the grated beetroot.
Beat two eggs with a little milk. Season with salt and pepper and mix with other ingredients.
Add to pastry case and top with grated parmesan cheese.
Cook at 180°C/350°F/gas mark 4 until set.
Mix horseradish sauce with an equal volume of creme fraiche (or plain yoghurt if you're on a health kick).
Serve beetroot tart warm with the horseradish cream and salad.