Peel and finely chop the onions. Rinse the gooseberries. Caramelize the sugar in a saucepan, then add the diced onion and gooseberries. Add the mustard seeds, and bring to a boil, stirring constantly.
Add the white wine and the broth and cook for 20 minutes over medium heat. Season to taste with salt, pepper, and vinegar. Serve as an accompaniment to cheese.