To prepare the beets for roasting, scrub under cold running water to remove any dirt, sprinkle with a little oil and season with salt and pepper. Wrap each beetroot individually in foil and roast in a preheated, moderate to hot oven 375F for around 40 minutes. To test if ready, push a skewer into the larger of the beetroots, there should be no resistance. Remove from oven and cool for 20 minutes. Peel away skin by pushing skin away using fingertips, however not necessary if scrubbed well.
Peel the skin from the celeriac bulb and then slice into ½ cm rounds. Slice into thin julienne strips and toss in lemon juice to prevent browning. Combine the celeriac with the mayonnaise and mustard, mix well and allow to sit for 20 minutes.
Pre heat the Crux griddle plate to a medium high heat
Once hot, place the haloumi on to cook for 2- 3 minutes on either side till golden, remove and set aside
To serve place the beets in with the celery root and very gently toss, scatter over the mint leaves, orange segments and haloumi. Scoop out individual portions onto salad plates or bowls.