1. Place onions in net boiling bag.
2. Place water, sugar, lemon juice, seasonings, and the net bag in large fish pot or double roaster pan. Over two flames, bring marinade ingredients to a low boil, then lower and simmer for 20 minutes.
3. Add fish slices, cover, and simmer for an additional 20 minutes.
4. Cook additional broth and slices according to need.