Trim beetroot stalks, leaving 1cm stem on the end. Wash thoroughly. Place unpeeled beetroot in a saucepan with vinegar, brown sugar and bay leaf. Cover with cold water and bring to boil. Reduce heat and simmer until tender, about 20 minutes (depending on their size). Drain, cool, cut off ends and peel away skins. Cut into halves or quarters if very large.
For the farro, bring a saucepan of salted water to the boil. Add farro, return to the boil, reduce heat to low and cook until tender (10-15 minutes). Drain and set aside to cool.
For the walnuts, blanch in boiling water, immediately remove and drain. Toss in caster sugar and shake away excess. Deep-fry walnuts in vegetable oil until caramelised (about a minute). Set aside on paper towel to cool.
For the dressing, whisk all ingredients in a bowl to combine.
Mix farro, walnuts and half the dressing. Divide among four plates, place gorgonzola and beetroot on top. Drizzle with remaining dressing and garnish with dill.