'TexMex' style cooking is the combination, I suppose, of the spices of Mexico and Italy with the dishes of Texas. Neither Texans not Mexicans will admit that these recipes have much to do with 'their' foods, but the style is wildly popular in the middle part of the western United States (Colorado, Utah, Wyoming, etc.) Many more tomato products are used in this style than anywhere in Mexico proper, and a very different selection of chili flavorings than in 'Southwest' cooking found in New Mexico. The 'California' style is another world entirely, and best left out of the conversation - like religion and politics!
Recipes for TexMex style:
Chili Verde (Green chili - pork and hot peppers),
Chili Colorado (Red chili - beef and beans),
Chicken Enchiladas (in tomatillo sauce),
and
OreoŽ Cookie Torte (not TexMex)