Heat 3 tablespoons oil in a large saucepan or skillet.
Fry the onion for about 6-7 minutes, until the onion is soft.
Add the garlic and fry for a few seconds.
Add the rest of the spices and mix for a minute.
Strain the can of olives over a bowl, add the olives to the sauce and mix well.
Add water, olive brine, preserved lemon, lemon juice, green chili pepper, chopped coriander, and mix. Taste and adjust seasoning if necessary.
Bring to a boil and reduce to medium-low heat.
With wet hands, form the mixture into balls about the size of falafel balls (about 3 cm in diameter (1.2 inch) and transfer to the sauce.
Cover the top of the meatballs with the sauce using a spoon.
Cover and cook for fifteen minutes, occasionally gently shaking the pan. After about fifteen minutes, remove the lid, increase the heat a little, and cook for another five minutes until the sauce thickens.