Take 3 large raw mangoes, peel them, and cut them into medium-sized pieces.
Add 800 g (about 5 cups) of mango pieces to a mixing bowl. Add 1 tbsp turmeric and 2 tbsp salt. Mix well, cover, and let it rest for 30 minutes so the turmeric and salt are absorbed into the mango pieces.
Now add 400 g (about 2½ cups) jaggery and 400 g (about 2½ cups) powdered sugar. Mix well and let it rest until the jaggery and sugar completely melt.
Place a kadai on the stove and cook the mixture on low flame, stirring continuously. Cook until the mango pieces turn transparent and the sugar syrup reaches a one-string consistency. This takes about 20–25 minutes.
Add 1 tbsp lemon juice and mix well. Let the athanu cool completely.
In a pan, add ¼ cup coriander seeds and 2 tbsp fennel seeds. Roast them lightly. Let them cool, then transfer to a mixer jar. Add ¼ cup rai na kuria and 2 tbsp methi na kuria, and pulse to make a coarse mixture.
Transfer this masala to a plate and add 1 tsp hing in the center. Heat ½ cup oil, let it cool slightly, then pour it over the hing. Cover and let it rest for 2–3 minutes.
Once the masala has completely cooled, add ¼ cup red chilli powder and mix well.
Add the prepared masala to the cooled athanu and mix thoroughly.
Your Instant Katki Gor Keri pickle is ready. Store it in an airtight container. It stays fresh for up to 1 year when refrigerated.