Heat the olive oil in a large frying pan. Season the prawns and set aside. Cook the garlic over medium-low heat until it just starts to colour. Increase heat to high and add the prawns and chilli. Stir quickly and keep turning prawns in the pan.
After 1 min, pour in the lemon juice. Toss until prawns are opaque – about 1 min more. Sprinkle over lemon zest and parsley and serve with crusty bread.