How to Make It
Preheat the broiler to high. Prepare the Fish: Combine the first 5 ingredients in a small bowl; stir in 1 tablespoon canola oil, agave nectar, and minced garlic. Rub the mixture evenly over the fish; let stand 15 minutes.
Prepare the Corn: Line a small baking sheet with foil. Arrange the corn at one end of the prepared pan; brush one side of each ear with 1 tablespoon melted butter. Broil for 5 to 6 minutes or until blistered. Turn the corn over; brush with the remaining butter.
Place the fish on the opposite end of the baking sheet from the corn. Broil 6 minutes or until the fish is done and the corn is blistered. Stir the zest into the crema. Combine 1/2 teaspoon salt, 1/8 teaspoon smoked paprika, and pinch of cayenne; sprinkle evenly over the corn. Drizzle the crema on the corn and top with the green onion.
Prepare the Slaw: Toss the avocado with the juice. Place the cabbage, tomatoes, and 2 sliced green onions in a medium-size mixing bowl. Add the avocado mixture and 2 teaspoons canola oil to the slaw; toss. Season to taste with salt and pepper.
To serve, break the fish into chunks and build the tacos with fish and slaw. Serve with the corn.