Peel and boil the potatoes in salted water until soft.
Drain, keeping about 1/2 cup of the cooking water.
Mash the potatoes and beat in the olive oil.
Add salt and pepper to taste and enough of the cooking water to have a soft, slightly moist texture.
Then stir in the parsley.
Fold in 3 tablespoons capers, soaked in water then drained and squeezed, or 5 chopped scallions.
Fold in some chopped black or green olivesabout 12.
Add 1/41/2 teaspoon turmeric to the cooking water, or 1/2 teaspoon harissa (page 464) at the end.
Add 1/2 teaspoon cumin, 1/2 teaspoon paprika, 3 tablespoons chopped cilantro, and the juice of 1/2 lemon or the chopped peel of 1/2 preserved lemon (page 459).
With sweet potatoes, add 1 teaspoon ground ginger to the cooking water,then pinches of powdered saffron,cumin, and chili when you mash the potatoes.
Use chopped cilantro instead of parsley,and if you like add 1/2 preserved lemon peel,chopped.
A spiced baked-potato puree comes from Algeria: Peel, boil, and mash 2 pounds of potatoes, then mix with 3 large eggs.
Season with salt and pepper, 2 teaspoons cumin, 1 tablespoon paprika, and, if you like, 1/2 teaspoon chili pepper, and stir in 1/23/4 cup chopped parsley or cilantro.
Pour into a baking dish and bake at 400F for 25 minutes.