Chop the onions, fry them in olive oil until translucent, add tomato paste and roast briefly, deglaze with a little water. Add the ketchup, balsamic vinegar and honey and let everything simmer briefly. Season the sauce with soy sauce, curry and chilli and dilute with a little water if necessary.
Cut the sausages into slices, pour the sauce over them and sprinkle with more curry.