Place the chicken, shallots, peppers, cilantro stems, and egg yolk in a large bowl. Add the masa harina, chili powder, cumin, cayenne, coriander, and 1 tsp of the salt and, using a clean hand, mix everything together until cohesive. The mixture should feel dense and a little springy. Cover and chill until ready to use.
When ready to stuff the blossoms, use a tablespoon measure to portion out the chicken mixture. Roll each portion into a cylinder and place them inside a blossom. Close the petals around the meatball and gently squeeze, as you would a tube of toothpaste, to coax the meat mixture into the base of the blossom. Twist the petals to seal and set aside. Repeat with the remaining blossoms.
Once all the blossoms are stuffed, you can start heating your oil. Pour the canola oil in a large dutch oven and place over high heat. Heat the oil until it registered 350°F. From here you will have to frequently adjust the heat to keep the oil between 350°F and 375°F throughout the frying process.
While the oil is heating up, make the batter. Place the flour, cornstarch and remaining salt in a large bowl and whisk to combine. Add the egg white and carbonated water and whisk until smooth.
Once the batter is mixed and the oil is ready, dip the blossoms into the batter before transferring them to the oil. Fry the blossoms until lightly golden, about 5 minutes. Transfer the blossoms to a cooling rack placed on top of a baking sheet. Repeat with the remaining blossoms.
Once the blossoms are fried, it's time to start building the tacos. Wrap the tortillas in paper towel in a stack formation and place them in the microwave. Heat for 30 seconds - this will make the tacos more pliable.
Place the toppings, condiments, blossoms, and tortillas on the table and encourage people to build their dream tacos. Serve with a round of beers.