small handful basil leaves, torn into small pieces
1 large red onion, finely sliced
3 tbsp balsamic vinegar
1 tsp bicarbonate of soda
1陆 tbsp soft brown sugar
450g/1lb plain white flour
2 tbsp olive oil
1 tsp table salt
30g/1oz cold unsalted butter, diced
1 tbsp butter, melted
300ml/10fl oz buttermilk
200g/7oz Manchego cheese, diced
80驳/2戮辞锄 prosciutto, torn