In a small skillet, heat 1/4 cup of oil over moderate heat. Add 1 tortilla and fry until golden and crisp, turning once, about 2 minutes. Transfer the tostada to paper towels to drain. Repeat with the remaining tortillas.
In a food processor or blender, combine the tofu with the lime juice, honey, mustard and chipotle and process until smooth. Add the remaining 1/4 cup of oil in a thin stream and process until creamy. Transfer to a bowl. Stir in the orange and lime zests and season the dressing with salt and pepper.
In a large bowl, toss the cabbages, onion, carrot and cilantro; season with salt and pepper. Add all but 3 tablespoons of the dressing and toss. Set the tostadas on plates and mound the slaw on top. Add the chicken to the bowl, toss with the reserved 3 tablespoons of dressing and mound on the slaw. Garnish with lime wedges and serve.
A citrusy Riesling will complement this salad. Try one from New Zealand or Australia.