Trim fat from lamb and cut into 1 1/2 to 2-inch cubes. Toss with salt and place in a large tub to marinate.
Remove the skin from the ginger root using a teaspoon, discard skin. Cut in half; keep one half whole and dice the other, set aside.
In a blender add the water, Vindaloo Curry Powder ingredients, vinegar, 10 garlic cloves, whole 2-inch piece ginger and puree until blended. Pour over lamb and toss to coat. Cover and marinate 2 hours.
Preheat oven to 375°F. Mince the 4 remaining garlic cloves.
Melt ghee over medium heat in a dutch oven. Add onion, diced remaining ginger, garlic and saute until onion is translucent. Add the tomato paste and cook for another 2 minutes. Stir in the lamb and curry marinade, beef stock, curry leaves and bring to a boil. Cover and place in middle rack of oven. Bake for 2 hours or until lamb is fall apart tender.
Optional: while lamb vinadloo is baking, peel 3-4 white potatoes and chop into 2-inch pieces. Add to heavily salted water and cook until fork tender. Drain and add to finished lamb vindaloo, stirring to combine.
Serve topped with chopped cilantro over steamed rice or as is with or without potatoes.