Cut deep incisions into the chicken flesh with a small, sharp knife. Place the chicken into a bowl and sprinkle over the salt and the juice of two lemons, massaging into the chicken until well coated.
Whisk the yoghurt and tandoori spice mix in a bowl until well combined. Pour the marinade onto the chicken and massage into the flesh. Cover with clingfilm and chill in the fridge overnight.
Preheat the grill to high.
Lift the drumsticks from the tandoori mixture and gently shake off any excess. Place a wire rack over a roasting tin and lay the drumsticks upon it. Grill for 20 minutes, turning regularly, or until richly burnished and the chicken is cooked through. Add more lemon juice to taste.
For the dip, place all of the ingredients into a food processor and blend until smooth. Serve alongside the chicken drumsticks.