Make the Pico: Dice the onion and tomato and place in a medium bowl. Finely chop the cilantro and add to the onion and tomato mixture. Add in the lime juice and season with salt and pepper to taste. (This step can be done the night before and left in the fridge until ready to serve)
Make the avocado crema: In a food processor, combine all the ingredients for the crema. Process until smooth. Season with salt and pepper to taste and set aside.
Cut the haddock into 1–2-ounce portions. In a medium bowl, combine the cornmeal chili powder, cumin, and garlic powder. Coat each fish portion in the cornmeal.
In a non-stick skillet over medium heat, heat the canola oil. Cook the fish, flipping once, until the fish flakes easily, about 4-5 minutes.
Assemble the tacos. Serve the fish over heated corn tortillas. Top with Pico de Gallo, avocado crema, and any other desired toppings.