The recipe for the the Naivedya of Chana Daal and Green Mango(Kacha Amba) offered on the Vaishakh Pournima day is as follows.
Soak Chana daal in water to soften it, a minimum of four hours. If one cannot leave it soaked for long, use warm water, to soften it faster.
On the daal is softened, grind it, along with green mango(this adds sourness, so amount to be added depends on one's taste) and green chillies(as hot as you would prefer).
In a thick bottomed vessel, then heat cooking oil, and temper(make a tadka of) mustard seeds, curry leaves and some turmeric powder(haldi). Wait for mustard seeds to splutter.
Then add the ground paste, some salt and sugar as per your taste. Mix the whole thing well. And the Naivedya is ready to be offered.