Coat the bottom of a large Dutch oven or wide deep skillet with olive oil.
Over medium heat, brown both ends of the cucuzza until golden, about 3 minutes per side. Cook in batches if necessary, do not overcrowd the pan.
Once browned, transfer the cucuzza to a plate while you prepare the sauce.
Sauté the minced onion, garlic and red pepper flakes (optional) in the remaining oil in the pan.
Pour in the tomato purée and fresh basil leaves. Add about 2 cups of water to the jar or can that contained the tomatoes, swirl it around to gather any excess tomato purée and add to the pan.
Bring to a boil, then lower to a simmer. Nestle the cucuzza pieces in the sauce, they do not need to be fully submerged in the sauce.
Simmer loosely covered for 2 hours, until the cucuzza is tender. After 1 hour, flip the cucuzza pieces to ensure even cooking. Adjust the seasoning if needed.
You are now ready to boil your favorite pasta and enjoy this cucuzza meal!