Place the salmon and prawns in a bowl with the spices, chilli flakes, half the garlic, 1 tbsp lime juice and 1 tbsp olive oil. Mix until the salmon and prawns are well coated, then cover and leave to marinade at room temperature for 20 minutes.
Mix the remaining garlic and oil with the tomatoes, pomegranate seeds and coriander in a small bowl. Stir in 1 tbsp of lime juice and season to taste.
Roughly chop the avocado flesh into a bowl. Add the remaining lime juice and plenty of freshly ground black pepper, then roughly mash with a fork.
Heat a non-stick pan, add the salmon and prawns and cook for 3-4 minutes, turning occasionally, until the fish just flakes and the prawns are piping hot and lightly charred. Warm the tortillas according to the packet instructions.
Serve the warm tortillas alongside the smashed avocado, salmon, prawns and salsa, and let everyone build their own. Garnish with the lime wedges and reserved coriander.