Again with Ottolenghi:
This is a radical simplification of a recipe from Ottolenghi's Jerusalem, which was delicious the way I did it, though I'm sure it would be better the way he did it. Only more expensive and harder. I left out saffron, and substituted an onion for leeks and shallots.
How to make Pistachio Soup:
(This serves three or four as an appetizer) Preheat the oven to 350. Shell half a pound of pistachios; you should have about a cup of pistachio nuts after they're shelled. Boil the nuts for one minute and then while they're still hot use your thumbs to rub off the skins. You won't get all of them, but the soup will be a prettier color if you get most of them. Roast the pistachios on a cookie sheet in the oven for 8 minutes.
While the pistachios are roasting, melt half a stick of butter in a medium-size saucepan and slowly saute one chopped onion in it until it's soft. While it's cooking, add some salt and pepper, a heaping teaspoon of cumin, half a teaspoon of turmeric (for color) and a teaspoon of grated ginger. When the onions are soft, add two cups of water and a chicken bouillon cube (or leftover chicken soup). Stir and simmer for about ten minutes.
While the soup is simmering, use a good immersion blender (better than mine), the food processor, or a mortar and pestle to grind the roasted pistachios into powder. Add them to the soup and use the immersion blender to puree the whole soup. Add the juice of one large orange and half a lemon, stir, and reheat before serving with a garnish of chopped parsley.
Vegetarian or Vegan?
If you want to make a vegan soup instead, make the soup the same way except instead of the chicken bouillon cube, put in a spoonful of Japanese miso.
Will it keep?
I think this would be better fresh. We didn't have any left, but the juice flavors wouldn't last well.