In a large bowl, whisk mayonnaise, lime juice, cilantro, and honey. Stir in jalapeño, cabbage, and corn; season with salt and black pepper. Cover and refrigerate until ready to serve.
In a medium shallow bowl, whisk olive oil, lime juice, chili powder, paprika, cayenne, and cumin. Add cod and toss to coat. Let marinate 15 minutes.
In a large nonstick skillet over medium-high heat, heat vegetable oil. Remove cod from marinade; season both sides with salt and black pepper. Cook fish flesh side down, turning halfway through, until opaque and cooked through, 3 to 5 minutes per side. Let rest 5 minutes before flaking with a fork.
Serve fish over tortillas with cornslaw, avocado, and sour cream alongside. Squeeze lime juice on top.
