Hard To Eat Out
If you want to try to best Mexican food there is, the best advice is to go to a market or eat street food. But if you are avoiding meat products, then that is not an option. First of all you will notice that options that seem in line with your diet are very limited, both on the street and in restaurants. On the street the options are usually limited to a fruit cocktail, vegetarian quesadillas, sopes (thick tortillas with beans, salsa, lettuce, cream and cheese) or other items without meat in them. In restaurants you will usually get these options as well as a salad, but the limited options can make eating out difficult. If you are eating out, be sure to ask if what you are ordering has meat as some things you would expect to be meat-free are not. Even if you are visiting friends and family you should not expect any vegetarian options other than guacamole. A lot of people are simply not familiar with a vegetarian diet and even if they have the best intentions to accommodate you, they could unintentionally include animal products in their cooking.
You would expect tacos to contain meat but what most people do not realize is that even a quesadilla with mushrooms and cheese will not normally be vegetarian. This is because most people, no matter if you are eating on the street, at a market or even in a restaurant, will make all tortilla based foods using manteca (lard). This means that even your seemingly vegetarian quesadilla is not so vegetarian. Now you would imagine that rice is vegetarian, right? If it is made by a typical Mexican cook, that is not the case. Almost all Mexican rice is cooked using chicken stock. The same is true for the delicious spicy chocolate sauce, mole. Even the re-fried beans you find both on the street and at a restaurant are not usually vegetarian.
Make Your Own Food
Because of the limited options and hidden meat, the best option if you are strict about not eating meat products in Mexico is to simply make your own food. The good news is that you can still make fairly typical meals, but substitute the meat for proteins such as soya or leave them out. If you make your own food, you will know that there is no meat hiding within it. One great thing about Mexico for vegetarians, however, is the wide range of fruits and vegetables. Although Mexicans love meat, they also love fruits and vegetables and you can find plenty of options here you have probably not seen before. This means that if you make your own vegetarian food, you will have many more options than you would anywhere else in the world.
A person who is a strict vegetarian and gets sick of making all their own food or eating fruit cocktails (the only truly meat-free street food) will have some options in larger cities. In larger areas, such as Mexico City, you can find a few great vegetarian restaurants that will make vegetarian versions of all the traditional Mexican food. This will give you a good chance to see what the authentic dishes taste like but still be true to your vegetarianism.