Pat dry the chicken legs with kitchen paper. Cut all round with a knife just below the end of the bone.
Push the meat down with the knife from the end of the bone so that a little bit of the bone is exposed.
Brush the drumsticks all over with the barbecue sauce, lemon juice and oil. Cover and chill in the fridge for at least 1 hour. Preheat the oven to 200°C (180°C fan, gas 6).
Spread out the drumsticks on a baking tray lined with baking paper. Cook in the preheated oven for 25 minutes until browned. Turn and brush with barbecue sauce. Sprinkle with sesame seeds and serve.