Here goes my family recipe of these traditional Piemontese delicacies.
For about 50 tiny round peppers (can be hot or semisweet, as you prefer)
Half a litre of white or apple vinegar
Half a litre of white wine
1 1/2 tsp of salt
About 200 gr of good canned tuna
80 gr of very good quality anchovies
Good Extra virgin olive oil
You will need plastic gloves if using hot peppers!
Wash the peppers and take away the stems. Wear your gloves and empty, so that you get rid of all the seeds and white bits inside (I use one of those tiny scoopers normally used for melon or watermelon).
Now bring the wine, vinegar and salt to a boil and cook the peppers for 5 minutes (calculated from the moment when the liquid boils again after adding the peppers). Drain and let cool upsidedown over a cloth.
Prepare the filling by putting the tuna & anchovies (desalted if needed).
When the peppers are dry and cool fill each of them with about 1 tsp of the filling and add a caper on top, pressing a bit.
Pack the stuffed peppers as tightly as you can without squeezing the filling out of them in glass jars and top with as much olive oil as it takes to cover them completely. Make sure that there are no pockets of air!
Close the jars and wait 3 or 4 weeks before eating them!