In a pot over low to medium heat, add a little oil and then add the chopped onions and garlic and pinch of salt. Let this cook for about 5 minutes or so. Add the red pepper flakes and spices. Cook for another minute of so. Add in the chopped tomatoes. Simmer this for about 10-15 minutes. Taste, season and add a little sugar if it is too acidic.
Add in the pieces of fish and the kale. Season lightly and cover with a lid or parchment. Let this cook for about 5-8 minutes or until the fish and kale is cooked.
Serve this with some pasta, add some torn basil leaves and drizzle with some extra virgin olive oil.