Celeriac, beetroot & blue cheese salad

Preheat the oven to 180ºC, gas mark 4. Wrap the beetroot individually in foil, put them in a roasting tin and cook in the oven for 1 hour-1 hour 30 minutes, until a sharp knife slips easily into the centre. Allow to cool a little, then peel away the skins and cut into thin wedges. Leave to cool completely.

Meanwhile, in a large bowl, whisk the mustard, vinegar and sugar, then season. While whisking, gradually add the oils to make a thick dressing. Add 1 tbsp water and whisk again.

Peel the celeriac and cut into pieces about 5cm long and 0.25cm thick (a mandolin is useful if you have one). As you cut them, throw them into the dressing. When the beetroot has cooled, fold it through, along with ½ of the walnuts, dill and salad onions. Leave to stand for 10 minutes, then transfer to individual plates or a serving platter and scatter with the blue cheese (we used Saint Agur here), remaining nuts, herbs and salad onions, adding a trickle more olive oil.