Preheat the oven to 400 degrees Fahrenheit, and line a baking sheet with parchment paper, or a silicone mat.
Add all the ingredients for the quick pickled onions in a bowl. Toss well, cover with plastic, and refrigerate until ready to serve the tacos.
In a large bowl, add the soyrizo and vegetable stock. Whisk until well combined. Add the cauliflower and beans, and toss well.
Pour cauliflower mixture on the baking sheet, and spread out evenly. Bake for 40 minutes, tossing three times during the cooking. You want the cauliflower to be tender, but not dried out. Remove from oven.
Heat a large skillet, or preferably a flat top over medium heat, and add a drizzle of one tablespoon of olive oil. Place four of the tortillas over the olive oil, using your hand to move them in a circular motion, coating one side of the tortilla well.
Add 2-3 tablespoons of filling on one side of the tortilla, and top with one teaspoon of cotija cheese, a few strands of pickled onions, and a sprinkling of cilantro. Flip the other side of the tortilla over the mixture, creating a taco shape. Let the tortilla crisp up on one side, about 2-3 minutes, and then carefully flip to the other side, and let crisp another 2-3 minutes. If you like it crispier, let it sit for a bit longer.
Repeat with the remaining taco shells and filling. Serve with extra pickled onions, cotija cheese, cilantro, and lemon or lime wedges.