Prepare Fish: Place the fish fillet on the prepared baking sheet. Drizzle with a little olive oil and rub to coat both sides. Sprinkle generously with cumin, salt, and pepper.

Bake Fish: Bake for 12-15 minutes, or until the fish is opaque and easily flakes with a fork. The exact time will depend on the thickness of your fillet. Once cooked, remove from the oven and set aside.

Make the Yogurt Slaw: While the fish is baking, combine all the slaw ingredients in a medium bowl: coleslaw mix, cilantro, lime juice, Greek yogurt, minced garlic, spring onions, and corn. Stir until well combined. Season with salt and pepper to taste. Set aside.

Fry the Tostadas: Pour about ½ inch of oil into a small skillet and heat over medium high heat. To test if the oil is hot enough, add a small piece of tortilla; it should sizzle immediately. Carefully place one corn tortilla into the hot oil. Fry for 1-2 minutes per side, until golden brown and crispy. Use tongs to flip. Transfer the cooked tostada to a paper towel lined plate to drain. Repeat with the remaining tortillas, frying them one at a time.

Assemble the Tostadas: To serve, place a crispy tostada on a plate. Top with a generous amount of the yogurt slaw. Flake the cooked fish into large chunks and arrange it over the slaw. Add optional toppings like a dollop of sour cream and slices of avocado. Garnish with extra cilantro and a lime wedge if desired. Serve immediately.