Beetroot and goat's cheese tart

Ingredients

• 1 tart case, baked blind
• 25 g unsalted butter
• 3 red onions, halved and finely sliced
• 2 tablespoons balsamic vinegar
• 500 g small beetroot, boiled, peeled and sliced.
• 1 small bunch spring onions, finely sliced
• 280 g goat's cheese log