Crush the chillies. Mix with the paprika and oil.
Place the tuna steaks in the chilli oil, turn to coat and marinate for 1 hour in the fridge.
Drain and chop the capers. Peel and dice the onions.
Drain the tomatoes and reserve 2 tbsp of the oil. Chop the tomatoes.
Mix the tomato pieces with the onions, capers, vinegar and tomato oil. Season with salt and pepper.
Wash the oregano, shake dry and roughly chop the leaves. Add to the tomato caper vinaigrette.
Remove the tuna from the marinade. Grill the steaks under a hot grill for 1 minute on each side until sealed but still pink inside.
Coarsely flake the tuna and mix it with the tomato caper vinaigrette. Stand for 15 minutes and serve.