In a large bowl, mix the mayonnaise, mustard and lemon juice together thoroughly with a generous sprinkling of salt and some freshly ground black pepper, so it all becomes one sauce.
Peel and quarter the celeriac, then, working quickly, coarsely grate it and stir into the sauce until evenly coated.
Serve the celeriac remoulade with lots of gluten free toast and some dressed watercress. It will keep in the fridge for up to 2 days.
Recipe from Good Food magazine
7 tbsp good quality mayonnaise
3 tbsp Dijon mustard
1 lemon, juice only
1 small celeriac, about 650g/1lb 7oz
Gluten free toast and watercress, to serve