When the onion is really soft, return the chicken thighs with any juices, the barley and stock. Gently simmer for about 40 minutes, stirring occasionally, until the barley is almost tender and most of the stock absorbed. If it gets at all dry during cooking, add a splash more stock. Stir the broad beans, kale, lemon juice and zest and seasoning into the barley, lower the heat and cover with a lid or baking sheet. Meanwhile, skin the chicken thighs and shred the meat from the bones using a couple of forks. Stir the chicken back into the barley with 75g of the crème fraîche and check the beans and barley are both tender.