On your way back from the mountain, the place to stop is this restaurant, very conveniently located, on the side of the highway. Look for carnitas.
When in Mexico, you should try las carnitas (the little meats), although they are nothing small, especially when you take into account the calories and lipid count. As Garfield once said, If it's not deep fried, it's not worth eating. Here, carnitas is a synonym of great flavor, wonderful food, and lots of calories.
Los Cochinitos (the little pigs) is a restaurant that specializes in... guess what? Pork meat deeply fried in its own lard with several presentations: gorditas, carnitas, etc., but they are all good. On their website, they will demystify some urban legends about pork meat and will explain about the fat, cholesterol, and calorie things, but none of that will change the flavor of their food.
Let’s go through their menu, as they only have it in Spanish, even on their website: Quesadillas (soft tortilla with melted Oaxaca cheese), cochinitas (maize tortilla with pork meat), lechoncitas (same as previous one, but with melted cheese), mixiote (steam-cooked ram meat with species - great), mixiote de nopal (similar to the previous one, but for vegetarians, as its main ingredient, instead of meat, is nopales, which is cactus), chicharron (mhhh, deep-fried, crunchy pork skin - a major snack), milanesa (thin breaded beef filet), carne asada (grilled beef steak), and enchiladas (Mexican specialty - maize tortillas stuffed with chicken and served in hot green tomato salsa).
Sorry for translating part of the menu, but you need to know what I'm talking about (and there are some more items left, but there is not enough space to write about those). The restaurant is always busy on weekends because its food is great. When I was a little kid, it was just a simple restaurant on the side of the road, but now it has two more locations, one as far as the southern part of Mexico City in a nice neighborhood. The one located on the road to the volcanoes is huge, can accommodate more than 200 persons, and has a big parking lot, but even then if you arrive at lunchtime, you will have to wait for a table. The waiters are efficient and the owner has already automatized the ordering system - good for them, and for us when you are hungry and don't want the waiter to take hours just to write down your order. Prices are okay. They are a little bit on the high side but really worth it. They accept credit cards.
Their website is Los Cochinitos>