Mix together beef stock, water, tomato puree in a stockpot
Add onions, carrots, celery, and parsley and bring to a simmer
After several minutes, add the mountain chain tripe. Simmer for 2 hours
Strain the stock with a spider, discarding the vegetable matter and returning the mountain chain to the stock.
Season stock, add book tripe and simmer for 90 more minutes
Chop tripe and serve in saltless Tuscan bread rolls with salsa verde and Calabrian chilies or chili oil