Place the mustard seeds in a strainer, wash under running water and soak for 1 hour. Drain and keep aside.
Wash the mangoes, peel and cut them into cubes.
Dry roast whole red chillies in a frying pan for few seconds, allow to turn them little darker in color. Please don’t burn, keep an eye. Remove from heat and keep aside.
Heat 1 tsp mustard oil in the frying pan. Add curry leaves. On low flame fry them for a minute or until they turn dark green in color. Drain on tissue paper and keep aside.
In a mixer/grinder add mustard seeds, green chillies and roasted red chillies. Mix until a coarse mixture forms. Transfer this into a mixing bowl. Keep aside.
Now add mango cubes in the mixer/grinder. Grind for a very short duration. We need to keep our raw mango pieces a bit chunky. So, care should be taken not to convert them into pulp.
Transfer this mango mixture into the same mixing bowl where we kept the mustard seeds paste.
Now add the rest of the ingredients (salt, sugar, crushed garlic cloves, mustard oil, turmeric powder and fried curry leaves) into the mixing bowl.
With the help of a spoon give this a good mix. Check salt. Store in sterilized glass containers.
Keep this condiment in the sunlight for 2 days. After that keep refrigerated. Use a dry spoon every time.