Cut the tomatoes lengthwise, without dividing the tomato into two pieces and fill with plenty of rock salt.
Keep these tomatoes aside while preparing the herb filling. Place them in a bowl and let them rest for 30 minutes to release juices. Don't throw this juice away. We are going to use it.
Add the coriander leaves to a blender along with green chilli, garlic pods, asafoetida, ground fenugreek and juice of 2 lemons. Blend this into a fine paste.
Fill each tomato with 1 tbsp of this herb paste, close both halves and place it in a glass container.
Place some more coriander leaves in the container and pour in the juice that the tomatoes released during the rest. We are not going to add additional salt water at a later stage. Rest these tomatoes for 24 hours.
The next day, you will notice that the tomatoes have released more juice. Let stand for another 24 hours.
On the third day, the tomatoes will have released as much juice as possible.
Mix 1 tsp of salt in a glass of water, and fill the jar up to the neck with this salted water.
Close the container and leave to ferment in a cool, dry and dark place for 10 more days.