Preheat the griller to high. To make the sauce, seed and halve the capsicums lengthways. Halve the onion across. Put both under the griller, skin sides up, with the unpeeled cloves of garlic. Grill for 10 minutes or until the skins are slightly charred.
While the vegetables are grilling, seed and chop the chilli. Dice the bread. Grate the rind of the lime and squeeze the juice.
When the grilled capsicums, onion and garlic are cool enough to handle, peel them and put the flesh into a food processor with the chilli, bread, tomato paste and 2 tablespoons olive oil. Add half the lime rind and juice, reserving the rest. Process the mixture to a purée, then season to taste with salt and black pepper. Transfer the sauce to a serving bowl and put aside.
Brush a ridged griller plate or a large, heavy-based frying pan with the remaining oil and place over very high heat. Lightly season the fish steaks and fry for 4–6 minutes, until golden brown on the outside and cooked through, turning once.
Sprinkle the steaks with the remaining lime rind and juice and serve with the capsicum sauce, either spooned round the fish or offered separately in a bowl.
The sauce is best served slightly warm, but it can be made in advance and served cold.
NUTRIENTS PER SERVING:
good source of vitamins A, B group, C and E, and selenium.
This dish is suitable for barbecuing. Start by grilling the capsicums, onion and garlic then finish off the sauce while the tuna is cooking on the barbecue.