Heat 4 inches of canola oil in a pot over medium-high heat. Clip a deep-fry thermometer on the side and bring oil to 350F, adjust heat to maintain this temperature.
In a large bowl whisk together the flour, salt, garlic powder, soda, black pepper, and cornstarch.
Stir the beer into the flour bowl, whisk until combined adding additional beer or flour until the batter is just slightly thinner than that of pancake batter.
Turn the oven to 175F. Place a wire rack over a baking sheet, add the baking sheet to the oven.
One at a time dip the florets into the batter until well coated, allow the excess to slip off back into the bowl, then add to the hot oil. Fry until golden brown on all sides, about 4 minutes, then transfer to the baking sheet in the oven to keep warm until all cauliflower is done.
Add all the sauce ingredients to a pot over high heat. Bring to a boil, stirring occasionally, until the sauce has thickened, about 3 minutes
Add the cauliflower to the tortillas, drizzle with sauce, sprinkle with green onions and nuts. Serve immediately.