The best tuna burger

INGREDIENTS

• 600 g fresh tuna steak, from
• , ask your fishmonger
• 1 sprig of fresh basil
• 1 sprig of fresh mint
• 4 spring onions
• 1 pinch ground coriander
• zest and juice of 1 lemon
• 1 fresh red chilli, finely chopped
• olive oil
• sea salt
• freshly ground black pepper
• 1 handful round lettuce, leaves separated, washed and dried
• 1 handful rocket leaves, washed and dried
• 2 tomatoes, washed and sliced
• 4 ciabatta or hamburger buns
• 1 lemon, cut into wedges, to serve
• tomato ketchup, to serve