2 1/2 pounds boneless skinless chicken thighs 1 lemon, juiced  Kosher salt 1 cup cashews, plus more for garnish  1 teaspoon coriander seeds 1 teaspoon cumin seeds 6 cardamom pods  5 black peppercorns 4 whole cloves  2 large onions, chopped  3 to 4 cloves garlic One 2-inch piece fresh ginger, peeled and finely chopped 3…