For the lamb: – 3-5 pound boneless leg of lamb – 1 tbsp mustard seeds – 1 tbsp coriander – 1 tbsp cumin – 1 tsp peppercorns – 2 tsp kosher salt – 4 garlic cloves – Leaves of 1 rosemary sprig – Leaves of 2 thyme sprigs – 2 tbsp olive oil – Ghee or butter for searing For the salsa verde (optional): – 1/4 cup chopped parsley – 1/2 tsp flaked sea salt – Juice of half a lemon – Zest of one lemon – 2 tbsp olive oil