Heat a pan and dry roast the sesame seeds till they splutter and transfer it to plate.
Re-heat the same pan adding oil, chana dal and urad dal. Roast the lentils till they turn slightly brown. Transfer them and again roast fenugreek seeds along with red chillies till the fenugreek changes color.
Add all the roasted ingredients in to a mixer jar along with grated coconut and grind together in to fine paste.
Heat a cooking pan / vessel with chopped hog plum pieces and it's seed. Cook it in 1 cup water and jaggery. The hog plum pieces become pale and soft when cooked. It takes very few minutes to cook.
Now add the ground paste in to cooked hog plum, stir it well. Add salt and bring the curry to boil. Switch off the flame.
Sour,sweet hog plum gojju is ready. Serve it with steamed rice, idli and dosa.