Preheat your oven to 425F. Using a paper towel remove any excess moisture from your whole rack of lamb and then let rest to room temperature while you prepare the Tuscan paste.
In a mortar (or in a small food processor) use your pestle to grind the garlic, rosemary, preserved lemon, Kosher salt, and black pepper into a thick paste. Mix in the extra virgin olive oil to combine all of the ingredients.
Generously coat the Tuscan paste all over the whole rack of lamb and let sit to marinate for about 30-45 minutes on a sheet pan. Once set, cook the whole rack of lamb in a 425F oven for about 15-20 minutes to develop an outer crust.
Heat a small frying pan over medium heat. Add about a ½ teaspoon of extra virgin olive oil and toast the pine nuts until fragrant. Once slightly golden, stir in the breadcrumbs to gently toast. Be sure to keep stirring the ingredients in the pan so they do not burn. Transfer the pine nut and breadcrumb mixture into a bowl and stir in the mint chiffonade and lemon zest.
Remove your whole rack of lamb from the oven once it reaches an internal temperature of 125F. Let rest for about 30 minutes to reach the medium rare temperature of 135F.
Once rested, serve slices of your Tuscan whole rack of lamb to friends and family with the breadcrumb-pine nut crumble on top.