The Triangle sandwich is a food item given by the Sandwich lady. It can also be acquired by pickpocketing the workers around the Tower of Life, granting 8 Thieving experience, or by searching the crates inside the tower. You can put one in a satchel.
The triangle sandwich heals 6 hitpoints when eaten.
The Triangle sandwich can be obtained by pickpocketing the constructers ('Black-eye', 'Gummy' and 'The Guns' at the Tower of Life, south of Ardougne.