Pat halibut dry and coat both sides with taco seasoning. Heat olive oil in a skillet over medium-high heat. Sear halibut for 2–3 minutes per side until golden and cooked through. Set aside to cool slightly.
In a bowl, combine black beans, corn, red onion, cilantro, and diced chili pepper. Add lemon juice, salt, and pepper. Toss well.
To build your bowl, start with a base of shredded cabbage, add sliced avocado, then place the halibut on top. Spoon over the bean and corn mixture.
Sprinkle with cotija cheese and drizzle with jalapeño ranch dressing. Serve immediately.
