In a large pan, melt the butter over medium heat. Add the leeks, garlic and 1 1/2 teaspoon salt and cook for 4-5 minutes, or until the leeks are softened.
Add the bread and paprika to the pan. Stir well to coat. Cook until the bread is lightly toasted, stirring occasionally to prevent the garlic from burning.
Add the wine, stocks and red pepper. Bring to a boil and then reduce the heat to a simmer. Let the soup simmer for about 10-15 minutes.
Meanwhile, in a small bowl, combine the shrimp, oregano and 1/2 teaspoon salt. Stir well to combine. Add the shrimp and the lemon zest to the soup and let it cook through, about 4 minutes. Serve warm with fresh thyme leaves.