Heat the oil in a saucepan, add the onion, garlic and bread and cook over a medium heat, stirring frequently, for 3–4 minutes.
Stir in the tomatoes, stock, peas, pimentón and sherry and bring to the boil. Reduce the heat and cook over a medium heat, stirring occasionally, for 3–4 minutes.
Add the prawns and cook, stirring, for 5–7 minutes or until the prawns turn pink and are cooked through. Remove the pan from the heat and season to taste with salt and pepper.
Ladle into warmed shallow bowls, scatter over the egg and parsley and serve immediately.