I've found this trick worked (a few years ago now) for a couple of trials where I wanted to use just flour and water. I think the boiling water makes the flour more elastic.
I've done a fair amount of experimentation on on bread making, and a very important step in bread making is autolyzing[0] the flour and water (letting the flour and water rest for a period after combining them).
However, the only reason water temperature matters in autolyzing is because you want an optimal temperature for yeast at the end of the autolyzation process[1].
More likely, what matters more is not the temperature of the water (assuming distilled, pure water, not subject to local tap water differences), but the time you let it the flour and water autolyze. My suspicion is that even though tortillas don't involve yeast, autolyzation is still important for optimal results.
NINJA EDIT:
Interesting, after doing some more research, I discovered boiling water is actually used to gelatinize flour--resulting in much more elastic dough, as you specify[2].
[0] https://www.kingarthurflour.com/blog/2017/09/29/using-the-au...
[1] https://www.weekendbakery.com/posts/a-few-tips-on-dough-temp...
[2] http://thebreadmaiden.blogspot.com/2016/02/the-science-behin...
I am dying for some good traditional tacos. (Currently abroad but far from Mexico)
The best tortillas I had were the handmade ones, made from organic blue maize.
I mostly lived in Mexico City, but I've traveled a lot around the country and spent time living in a few other cities for shorter periods of time. I've probably seen more of Mexico than 90%+ of all Mexicans.
Some of the best food I've ever had was in a small Pueblo (town) called San Sebastián del Oeste in the state of Jalisco. [1] It's a small "magic town" in the mountains in Jalisco. [2]
Most of the best food I've had in Mexico was not in the big cities but in the small towns. Especially, the family-owned places where there's an older Mexican lady cooking up food. Cliché but true.
[1] https://en.wikipedia.org/wiki/San_Sebasti%C3%A1n_del_Oeste [2] https://en.wikipedia.org/wiki/Pueblos_M%C3%A1gicos
Current recipe
130g flour
80g hot water (steaming)
35g lard
1g salt
Twice as much baking powder as what you see in salt (it weighs less so I don't see it registering on the scale)
Depending on your location, you may use 120-125g flour, 80g water because the water/environment is just different.
1. I typically place a pan on a scale and then put in 35g lard (pork and duck have worked well for me), then I put the pot on the lowest heat to melt. Fat is key, I tried using oil, butter, etc in the past and it didn't work well for me. It's also possible because I was butchering all the other steps too, this is what I call my cracker tortilla days :(.
2. Next I put on my kettle for hot water (80+ grams worth), it's fine if it boils but you mostly just want hot steaming water.
3. I put a bowl on the scale and pour in 130g of flour. Flour of course is another key element since not just any flour gets the job done, I've been experimenting and having some success with flours in Europe though that are more artisan bread friendly. Here are some Mexican ones https://allofeverythingblog.wordpress.com/2014/04/16/autheni... that you want to look for and you can also try to order some online (white sonoran wheat flour). Weirdly enough, there is a difference with El Rosal in America vs the ones from Mexico, the American ones are enriched and bleached which gives it a slightly diff dirt like smell and flavor. I recommend finding a way to get the flour from Mexico if possible.
4. I take the pot with fat off the fire, let it sit for a 1-2 mins.
5. I take the hot water off the fire, and pour it into a mug on my scale, looking for 80g of weight.
6. I put the baking soda and salt into the fat, along with the hot water from the mug, stir it up so it's all mixed.
7. Pour in the flour and mix it a bit with a fork, then knead it like you're folding the dough on itself for about 5 minutes. At first it may stick to your hands but after a minute or so that should go away, if it doesnt you need to add a tiny bit of flour, or water if its too dry. This is hard to explain since its more a feel. After 3 sessions or so you start to understand the consistency you're looking for.
8. After 5 minutes you should have a smooth dough that you can then pinch off into 8 tiny golf balls. If you let the dough sit here, which isn't necessary, (I've tried as long as 4 hours) it becomes quite elastic which makes it harder to press/roll the tortilla to a manilla folder thin thickness.
9. Roll them into a ball and then I recommend using a press with baking sheets so they dont stick, but you can also use a rolling pin.
10. If using a rolling pin, roll it up and down into a rounded button like shape, then turn that horizontal and do it again with equal pressure on both sides of the pin, this should result in a circular shape. I don't recommend adding flour since that will result in a more floury taste, but I'm still trying to figure out how to get around this without a press, since the tortilla will stick to your surface without baking paper. I don't recommend foil/plastic because the creases will reflect in your tortilla. At the end of rolling, they should be pretty thin (manila folder thin)
10. Make sure your pan is on medium high heat, takes about 5 minutes to get there, sometimes longer if using a cast iron. Then place your tortilla on the pan, it should bubble within 20 seconds, then you can flip it wait another 15-20, then flip again. This is pretty crucial, if the heat is too low its undercooked with no bubbles, if its too high it burns and the little brown spots will crack as you try to roll your tortilla. Heat's probably one of the most important parts which took us about 50 tortillas to learn.
11. After that you can place it on a plate or in a tortilla warmer.
Hope this helps! In the future I'll probably look into corn but that's definitely once I perfect an entire taco first.
For those of us in Europe can you recommend your choice of flour (and perhaps some other replacement ingredients)
I would also avoid things like Maseca if you have the time to try to figure things out, since they are a pre mix just add water type thing for corn tortillas specifically.
Overall I'm enjoying the craft of it all and will be soon moving towards learning the details that go into making sauces and carne asada.