Florence's famous tripe sandwich dipped in broth and topped with salsa verde is bold street food. A high protein mediterranean carnivore staple that's been a family tradition at Florentine markets for generations.
Rinse the lampredotto thoroughly under cold water. In a large pot, add the lampredotto, celery, carrot, and onion. Cover with water and bring to a simmer over medium heat. Skim off any foam that forms.
Lower the heat to maintain a very gentle simmer. Cover partially and cook the lampredotto for 1.5–2 hours until tender, ensuring the water does not boil vigorously so the tripe remains tender and does not shrink.
While the lampredotto cooks, prepare the salsa verde: Finely chop parsley, capers, anchovies, and garlic. In a bowl, combine with olive oil, red wine vinegar, and a pinch of salt and pepper. Mix well to form a bright green sauce.
When the lampredotto is cooked, thinly slice it against the grain. Dip each roll quickly in the hot broth to soften the inside before filling.
Layer the sliced lampredotto generously inside each roll. Spoon salsa verde over the meat, add extra broth if desired, and serve immediately while hot.