Well, as Keanu said "I know that the ones who love us, will miss us."; he was a good man. Here is his recipe.
This is for a small batch (around 1 KG), you can scale this accordingly.
Ingredients:
1) Raw mangoes (Kairi): 5-6; washed, dried, and cut (retain skin, discard seed)
2) Mustard oil: 1 cup
3) Fenugreek (Methi), Fennel (Saunf), Mustard, Coriander seeds: 2 tbsp each, roasted and powdered
4) Asafoetida (Hing): 1/2 tsp
5) Salt: 3 tbsp (or to taste)
6) Kalonji: 2 tbsp
7) Turmeric: 1 tbsp
8) Red chili powder: 2 tbsp
Method:
1) Sterilise: Wash the jar and lid. Fill with water, boil for 5 minutes, then empty. Invert to dry.
2) Roast & Grind: Dry roast fenugreek, fennel, mustard, and coriander seeds. Let cool, then powder.
3) Mix: In a large bowl, combine mango pieces with spices, kalonji, chili powder, turmeric, asafoetida, and salt.
4) Oil: Heat mustard oil until it smokes, then cool to lukewarm.
5) Combine: Blend oil with the mango-spice mixture.
6) Store: Transfer the mixture to your sterilised jar. Ensure mangoes are submerged, adding more cooled oil if needed.
7) Ferment: Place the sealed jar in direct sunlight for a week.
8) Serve: Ready in a week. Always use a dry spoon for serving. Store at room temperature up to a year, ensuring no moisture enters.