Roughly chop coriander leaves and stalks. Place all ingredients into a blender and process until a smooth paste is formed. Use a rubber spatula to clean the sides of the blender and push the paste down. Remove the paste from the blender and keep aside.
Place calamari rings in a colander and leave to drain thoroughly.
Heat an electric wok or pan on high and pour in the sunflower oil.
Add calamari rings and cook on a high heat until the calamari changes colour. Some rings may turn a light golden brown. Season with salt.
Continue stirring until the moisture evaporates taking care not to overcook the calamari. Turn off the heat and stir the chermoula paste into the calamari rings. The rings should be evenly coated in the paste.
Lastly add sliced red onion, tomatoes, fresh coriander and a good sprinkling of black pepper.