When life gives you sour oranges, make marmalade. Actually, sour oranges are also known as Seville oranges and make great marmalade. Canning fruit, making jams and other preserving type stuff is something I know how to do, but never did it much. I am not a big jam eater, but I have all these sour oranges and so there you have it.
It's pretty easy, pick the 6 or 7 nicest naranjas agridas you have, wash them well. Slice them thinly, seed the slices, and put them in a heavy pot with about a quart of water. The seeds go into another smaller pot with a cup of water.
The small pot goes on the boil, for about 5 minutes, strain the liquid and add it to the big pot, discard the seeds.
Bring the large pot to a boil, let it simmer for 10 minutes. Turn off the pot, cover, go to bed, or whatever you want for about 8 hours or more.
Return the pot to a boil, reduce heat, simmer until the peels get tender.
If you are scientific, measure the liquid and add a cup of sugar for every cup of liquid, if you are me and lazy, dump in sugar until you feel that you have enough. Now cook until it's thick enough to jell. You may want to watch the pot, sugar water if it over boils makes a bit of a mess.
I use azucar standard