I can't speak for Denmark, but here in the US, one can buy tinned and jarred "Sweety Drops," or "Sweety Pepps." You can Google ingredients and find a recipe that works. I've used a family "sweet & sour" recipe originally intended for pickling cucumbers and chow chow successfully.
I'll do that, thanks a lot!
Todays harvest, I call it summer in a bowl
Peppers: Black is a pasilla from junaitospeppers, the white is a murupi amarela. Red is a fire flame pepper. Orange is Andy's King BOC. Yellow is Jamaican mushroom yellow, and the small red is Biquinho as pictured before