In a large stovetop pot, add water to the halfway mark and bring to a boil. Add in salt, spices, garlic cloves and the roasts. Cover and let boil for a minimum of 3 and half hours. Aim to cook for a good 4 hours. The meat becomes more tender the longer it is cooked. You'll know the meat is ready when it falls apart easily in the pot with tongs. Drain meat into a large colander and let cool for a few minutes (until easily handled). Using your hands, remove any remaining fat or bone (there won't be much), break apart into small pieces and place in a serving bowl. This will require little effort—the pot roast should easily fall apart. Note: roasts should always be fully immersed in boiling water. Check on the roasts every hour or so and add water as necessary to cover.
While the pot roast is cooking, prepare lime crema (see below) and taco fixings (chop onion, wash cilantro leaves, slice cabbage, crumble feta). Place in pretty serving bowls and set aside.
To serve, warm up corn tortillas over medium heat in a large dry stovetop pan for a minute or two on each side. Alternatively, wrap a stack of tortillas in aluminum foil and heat in a 350 degree oven for 10-15 minutes. Serve immediately with shredded pot roast and fixings. Enjoy!