Peel mangoes, cut lengthwise and remove kernel. Further cut into large pieces.
Heat oil in a non stick pan. Add fenugreek seeds, fennel seeds, onion seeds, turmeric powder, red chilli powder and grated jaggery and mix well.
Add mango pieces and mix well. Cook for 7-8 minutes.Remove from heat and cool. Serve as accompaniment or store in sterilized bottles.