Heat oven to 200C/180C fan/gas 6.
Peel the beetroot and cut each into
8 wedges. Cut the onions and butternut
squash into roughly the same size.
Spread out in a large roasting tin. Mix
the vinegar and sugar until dissolved,
then whisk in the oil. Pour over the
vegetables, toss and roast for 40-45 mins
until charred and soft, stirring halfway
To make the horseradish cream, mix
together the soured cream, horseradish,
lemon juice and some seasoning.
To serve, put the roasted veg in a
large bowl or on a platter, followed
by the watercress, then drizzle over the
horseradish cream. Serve warm or cold.