Peel the garlic. Wash it well and dry on a kitchen towel till no trace of water is there.
Heat enough oil in a kadai for deep frying. Drop the garlic in batches and fry briefly for a couple of minutes. Do not brown it. Drain it onto a kitchen towel. Repeat till all is done. Allow to cool completely.
Put the garlic into a bottle and pour vinegar till an inch above it. Add some salt and give it a good mix.
Roast the mustard and fenugreek seeds briefly. Pound using a mortar and pestle till coarse powder.
Mix the chilli powders and turmeric powder into a paste with little water.
Heat the coconut oil and splutter the mustard seeds. Briefly fry the minced curry leaves. Add the spice paste and give a good mix. Make sure the flame is on simmer so that the paste doesn't burn. Saute till the raw smell is gone. Switch off and allow to cool.
Pour 1/4 cup of vinegar into this mixture, add the pounded powder and whisk well. Add salt and mix.
Pour this into the soaking garlic and mix well. Add more vinegar if required. Allow it to rest for 24 hours.