In a pan, heat some oil over medium heat and add the sliced red onion. Sauté until the onion becomes translucent.
Add the garlic to the pan and cook for a minute until fragrant.
Stir in the canned crushed tomatoes and let it simmer for a few minutes.
Add the raw prawns to the mixture and cook until they turn pink and are cooked through.
Finish by stirring in the chopped parsley and serve hot.
