Aam Ka Achaar - Indian Green Mango Pickle

Ingredients (Makes about 16 oz)

1 lb green mangoes
2 tsp saunf (fennel seeds)
2 tsp methi (fenugreek seeds)
3/4 tsp kalonji (nigella seeds)
1/2 tsp yellow mustard seeds
2 tsp rai (brown mustard seeds)
1.5 tsp turmeric powder
1 tsp red chili powder (adjust to taste)
1/4 tsp powdered hing (asafoetida)
1.5 tsp Salt + more if required
250-300 ml virgin mustard oil,divided

**Notes - **

Never under salt the pickle, it will go bad within few weeks.
If you do not like the strong taste of mustard oil, you can heat it up to do away the raw smell, cool down and then add.
The kind of mangoes I used were really tart and so the pickle came out quite tangy. 
If you do not get pickling mangoes, add some amchoor (dry mango powder) to the recipe for a tart note.
This is not an instant pickle recipe, the pickle is sun fermented and takes 7-10 days to mature and get ready to consume.
Method

Wash and pat dry the mangoes. Cut and discard the top stem and then cut them into half, remove and discard the seed & membrane and then cut into small cubes.
Layer the cubes on a wide plate, sprinkle 1/2 tsp of salt and let sit in sun for 1-2 days till the skins starts to dry on edges and turning pale green.
At the end of the day, remove and discard any liquid that has collected.

Using your coffee grinder, coarsely pulse the saunf, methi,kalonji and mustard seeds. In a small bowl mix these with turmeric, chili and hing, mix well.

Place the mango pieces in a wide glass dish (I use my pyrex) and add the spices mixed before. Sprinkle the salt.
With a clean and dry spoon or fingers, mix well such that spices and salt loosely stick to mango pieces.
Add 150 ml of mustard oil and mix it well.
At this point, the achaar will have a very strong smell and a bitter taste but that's okay.
 Allow it to stand in full sun for two days. Try to stir the achaar once or twice a day with a clean, dry spoon.

On the third day transfer the achaar into a glass or porcelain jar, check and adjust the salt and top with remaining oil and mix well.
Cover the mouth of the jar with a muslin cloth, tie with a string and let mature for seven to ten days in sun.
( this time will depend on the strength of sun in the area you live).Stir the contents once or twice a day.

At the end of sun fermentation, the skin of the mango would be brownish and the strong, bitter taste will go away.
Store at room temperature for up to 10-12 months. Always use a clean spoon to serve the pickle.