1. Cut the fish into 2cm cubes and place in a medium bowl. Rub with salt and leave for 2 minutes.
2. Add all the citrus, chilli and garlic and leave to marinate for 10 minutes.
3. Meanwhile, soak the red onion in iced water for 5 minutes, drain, then gently stir into the fish.
4. Divide between two serving plates, scatter with coriander to your liking and drizzle with olive oil. Serve with the maize tostada on the side or sprinkle on top.
Recipe courtesy of Kenwood's Around the World in 80 Plates