Tetrazzini refers to an Italian dish typically made with diced beef or poultry in a rich cream sauce containing sherry. This is added to cooked spaghetti or noodles in a casserole and topped with bread crumbs or grated cheese .
Tex-Mexshort for Texan-Mexican refering to foods that combine Texan and Mexican influences in their tastes. Nachos and Burritos are examples of Tex-Mex foods.
Considering that Texas is already near Mexico, Tex-Mex foods emerged.