Heat the oven to 400[dg]F. Peel and chop the onion; chop the garlic. Put 1 tablespoon oil in a large skillet over medium-high heat. Add the onion and garlic and sprinkle with salt and pepper. Cook, stirring occasionally, until the vegetables soften, 3 to 5 minutes. Drain the tofu and refrigerate 1/4 of the piece for another use. Crumble the remaining tofu into the pan with your hands. Cook, stirring and scraping the bottom of the skillet occasionally and adjusting the heat as necessary, until the tofu is browned and crisp, 15 to 30 minutes, depending on the desired texture (see the headnote).
While the tofu mixture cooks, rinse the cabbage, bell pepper, carrot, cucumber, scallions, limes, cilantro, and avocado. Squeeze the juice from 1 lime into a large bowl and quarter the other. Add the remaining tablespoon oil to the bowl along with the cumin and a sprinkle of salt and pepper. Whisk until combined.
Core and thinly slice the cabbage; add it to the bowl and toss. Core and slice the bell pepper; peel and slice the carrot; trim the ends from the cucumber, halve it lengthwise, and cut each piece into thin strips. Add the vegetables to the slaw and toss until everything is coated in dressing. Taste and adjust the seasoning, adding more lime juice if you’d like. Chill the slaw until the tacos are ready.
Stack the tortillas on a large square of aluminum foil and wrap them loosely. When the tofu is almost cooked to your liking, put the tortillas in the oven to warm. Sprinkle the tofu mixture with the chili powder; continue cooking, stirring and scraping any browned bits from the bottom of the pan, until it’s fragrant, less than 1 minute.
Halve, pit, and dice the avocado. Trim and slice the scallion; chop the cilantro. To serve, fill the tortillas with the tofu chorizo, avocado, and scallions and garnish with the cilantro. Pass the slaw and lime wedges at the table.