Pulse 450g of walnuts in a food processor into fine crumbs, stopping before they turn oily.
Season 8 skinless bone-in chicken thighs with ½ teaspoon of turmeric, ¼ teaspoon of black pepper, and two-thirds of 1½ teaspoons of kosher salt.
Heat half of 4 tablespoons of olive oil in a large pot and sear the chicken until browned on both sides, then set aside.
Cook 1 diced onion in the remaining oil until golden. Add the walnuts and toast, stirring, for 5-15 minutes, until fragrant.
Add 6 cups of water and bring to a boil. Cover and simmer for about 1 hour.
Stir in 425g of canned pumpkin puree, 1½ cups of pomegranate molasses, and the remaining salt. Cover and cook for 1 hour more.
Return the chicken to the pot and simmer for about 30 minutes, until it reaches 165°F / 74°C and the sauce has thickened. If it tastes too sour, stir in a little brown sugar.
