Preheat the oven to 275 degrees F.
To a small bowl, add the lemon zest, chopped rosemary, kosher salt, to taste, sugar, and stir to combine. Season the racks on both sides with the mixture and set aside. Allow to sit in the refrigerator, covered, for at least 8 to 24 hours before grilling, if possible. This will act as a quick cure, adding more flavor to the lamb when it's cooked.
Place an oven-safe saute pan over medium heat and add the blended oil. Add 1 of the seasoned racks to the pan, fat cap-side down and sear until golden brown, about 3 to 5 minutes. Once the fat cap is golden brown, flip and place the whole pan into the oven until an instant-read thermometer inserted into the thickest part of the lamb, not touching the bone reaches 120 to 125 degrees F for medium-rare, about 20 to 25 minutes. Cook's Note: It's best to cook it low and slow at this point to help prevent that "bullet" from forming, where the middle is rare and the outside is well done.
When the lamb is done, remove it from the oven and set aside to rest for 5 minutes prior to cutting.
Slice the day old bread into large dice. Cook's Note: if you don't have day old bread, place the cubed bread into a 350 degree F oven to dry out, about 10 minutes.
Add the bread to a large bowl and cover with the milk, pressing the bread down to immerse it in milk. Set aside to soak.
Place a saute pan over medium-high heat and heat the blended oil. Add the sliced almonds to toast, about 2 minutes. Once slightly toasted, remove about 1/4 cup and set aside for the salad. In the same saute pan add the shallots, sliced garlic, and season with salt. Toss to combine and allow the shallots and garlic to sweat. Once the shallots and garlic are fragrant, remove them from the heat.
Add the soaking bread to a blender, allowing any excess milk to drip out. Cover with the extra-virgin olive oil and add the toasted shallots, garlic, almonds, lemon juice, and salt, to taste. Blend the mixture until pureed and smooth like a paste. Taste and re-season, if needed.
To a bowl, toss the orange supremes and the juice (collected when preparing the orange supremes), toasted almonds, salt, black pepper, and watercress. Drizzle with extra-virgin olive oil and toss to combine.
Slice the lamb into individual chops. Place a couple of spoonfuls of the skordalia onto a plate. Top with 3 of the chops and season each with sea salt to add a little crunch. Garnish with the salad. Season with freshly ground black pepper and drizzle the plate with extra-virgin olive oil and the orange zest.