Heat the oil in a large heavy saute pan over medium-high heat. Add the onions and cook until translucent, about 3 minutes. Add the cauliflower and saute until tender, about 5 minutes. Season with salt and pepper. Add the oregano. Turn the heat off and reserve. Heat a large heavy griddle. Working in batches, heat the tortillas one at a time until they are soft and pliable, about 1 minute per side. Add 2 tablespoons of warm Chorizo Refried Beans to the center of the tortilla, spreading outward to the sides. Add 1 tablespoon of the sauteed cauliflower mixture. Add 1 tablespoon of cheese. Fold in the edges and roll to form a burrito. Return to the griddle just for the cheese to melt, about 10 seconds. Serve warm.
Heat a medium saute pan on medium heat. Add the chorizo and cook until golden in color, about 6 minutes. Remove the chorizo to a drain on a plate lined with some paper towels. Add the onions to the pan with the chorizo fat. Saute until the onions are translucent, about 4 minutes. Return the chorizo to the pan. Add the refried beans to the mixture. Continue cooking for about 5 minutes. Turn the heat off and reserve for tostadas and burritos.