Put the sultanas into a small bowl, pour over some freshly boiled water, and leave them to plump up. Peel the onion and cut into fine half moons. Heat the oil in a large pan that can cope with all the raw spinach later (or wilt first as above), and cook the onion until golden and soft. Toast the pinenuts in a dry pan until they are colored and tip into a bowl to cool.
Rinse and drain the spinach if you haven’t wilted it already. Add the wine to the golden onions and stir well, then tumble in the spinach, pressing it down in the heat of the pan. Keep stirring to cook the spinach evenly. Let the spinach cook down, so that the water evaporates from the pan as much as possible.
Drain the sultanas well, and add to the pan along with the toasted pinenuts. Season with salt and pepper and add a little more olive oil if necessary.
You can do all this in advance of sitting down, then just put a little heat under it while you’re clearing the plates.