Angoor ka chutney

I did have a bunch of "iffy" grapes which I was thinking of mashing into curds and having. But since the idea got planted in my mind, decided to adapt my strawberry chutney recipe for grapes. At the last moment, googled to see if I could find any recipes, and found a few that required onions and mustard seeds.
Grapes and onions!!!! The combination seemed absolutely counter intuitive, so I had to try it out. Turned out to be quite different from what I thought a grape chutney should, but lovely all the same.

1 cup grapes quartered (half and half of green and red grapes was recommended, but I used a mixture of all the grapes that for various reasons get left uneaten)
1 medium onion chopped small
1 tsp mustard seeds
1 inch ginger grated
1 1/2 tbsp vinegar (less if grapes are sour)
1 1/2 tsp pepper powder
3 tsp sugar
salt to taste
cooking oil

Heat oil, temper with mustard seeds, and fry onions till they turn transparent.
Add grapes, ginger, vinegar and pepper powder, and cook for about 10 minutes.
Add salt and sugar, stir well, and cook for 2 - 3 minutes till most of the water released by the grapes evaporates.