Heat the oven to 190C/fan 170C/gas 5. Put the bacon on a rack over a baking tray. Mix the syrup, sugar and mustard in a small bowl with a splash of water, then lightly brush over the bacon. Cook in the oven for 10 minutes, then turn and brush the other side and cook for another 10 minutes. Keep brushing and turning until the bacon looks glassy, crisp and caramelised – this will take another 5-10 minutes depending on the power of your oven. Keep a close eye on the bacon for the last few minutes of cooking, because the sugar can easily burn.