beansmexican-cuisine
In the US, some Mexican restaurants and taco vans offer a choice of black beans served as a topping for tacos or tortilla salads. The black beans are not mashed, like refried beans, but served whole.
I bought some dry black beans, but they did not come in any easy-to-prepare can in sauce with instructions. How can I prepare them just as the restaurants do?
If you soak your beans in brine (3tbsp table salt per gallon of water, or 1.5% salt by weight) it'll help soften the skins by replacing calcium and magnesium ions in the skin. After soaking for 8–24 hours, drain and rinse. (Source: Cooks Illustrated, login required). Harold McGee in On Food and Cooking also mentions this (p. 488–489) and suggests 1% salt by weight. McGee also mentions that 0.5% baking soda will further reduce cooking times (but may lead to unpleasant taste & mouth feel).
Alternatively, Cook's Illustrated also reports that dried kombu can be used to similar effect, without needing the soak.
Even after brining, taste them when nearly done cooking: you may need to add some salt—it doesn't always penetrate that far into the beans. At least, that's been my experience.
Quick summary:
You want to season towards the end of the cooking because it results in creamier texture and also eating some beans which haven't been heated to boiling for 10 minutes is ill-advised due to phytohaemagglutinin.
Potatoes are very popular in some parts of Mexico. When I lived in Guadalajara, potato tacos were common, usually deep-fried. Diced (and possibly pre-cooked) potatoes with some seasoning added to a soft taco shell, then the entire thing fried together until crispy. After frying, such tacos (whether with potatoes or other filling) were cracked open to add lettuce or salsa or whatever other toppings/fillings might be desired, or salsa might be poured over the top, and eaten with a fork.
One of my favorite local dishes was gorditas, which are basically a double-thick tortilla split at the middle (like pita bread) and stuffed with a filling of choice, and grilled. Diced and cooked potatoes were a common choice, often with beans or cheese as well.
Potatoes are also common in Mexico prepared much the same as they are in the U.S.: Baked, or as french fries, or the ever-popular potato chip. Always with a Mexican flair, usually in the form of extra spicy seasoning or sauces added.
I also had a "Breakfast taco" in Austin, Texas a couple months ago, which had potatoes. So there is some tex-mex food with potatoes, but I think this is probably not as common as it is in true Mexican cuisine. But then, Tex-Mex has never been a very close substitute for true Mexican food :)
My best guess as for why potatoes are not common in Mexican and Tex-Mex restaurants in the U.S. is that potatoes are not considered an exotic/exciting enough food/flavor to be considered "special" by most people who frequent such places.
Best Answer
Dried legumes, including black benas, are generally soaked in water for at least 8 hours (or overnight) to begin softening them, then drained and simmered in fresh water until tender (usually at least 60-90 minutes). You can add stock or other seasonings during the cooking portion, or add the plain cooked beans into a sauce you've prepared separately.