In a stock pot over medium heat, render pancetta until translucent. Add carrots, celery, and onion and sweat the vegetables until they’re soft. Add garlic and thyme. When the garlic begins to brown, add ceci and enough water to cover the beans by 1-2 inches. Bring to a boil then reduce the heat to medium and cook until the ceci are soft, about 1 hour. Remove from heat. When the mixture is cool enough to handle, carefully remove thyme sprigs and vegetables. Add salt and pepper to taste.
Meanwhile, make the currant mustard. In a small pot, add blackcurrants and water and simmer until the currants are soft. Strain the currants and reserve the liquid. In a blender, add the currants and about half of the cooking liquid. Blend until smooth adding more water, if necessary. Combine blended currants and mustard and stir until it’s the consistency of syrup.
Season lamb with salt and pepper. On a hot grill or grill pan, cook on each side for 3-4 minutes until you reach an internal temperature of 115 degrees for rare, 125 degrees for medium-rare. Allow lamb loin to rest for 5 minutes before slicing.
Strain the black ceci and place in a sauté pan with olive oil, diced thyme, and salt and pepper. Sauté until warm. Add a tablespoon of lemon juice then transfer to a serving platter.
Cut the lamb loin into 1/4-inch slices and place atop the ceci. Drizzle the meat and ceci with currant mustard and olive oil. Finish with a sprinkling of sea salt and fresh thyme.