Moroccan fish balls tagine (طاجين مغربي كرات السردين)

This tagine is very famous in the Morocco as Morocco is known for its sardines
For this recipe we will need:
For the sauce
Extra virgin olive oil
One medium onion finely grated
2 cloves of garlic minced
Cumin seeds
2 medium tomatoes finely grated
2 tablespoons of tomato Passata
Salt/black pepper/paprika/chilli powder/ coriander powder/ ginger powder/ Cumin powder/ turmeric powder

For the fish balls we will need
One kilo sardines cleaned and descaled
And spine removed

2 cloves of garlic or garlic powder
A bunch of parsley
The same spices used in the sauce
1-2 tbsp of breadcrumbs

To decorate
Some fresh coriander
Chilli flakes
And extra virgin olive oil