The Tuna Burger

• 4 brioche rolls
• 1 seedless cucumber (peeled)
• 1 onion thinly (red very sliced)
• 525 gr yellowfin tuna fillets fine by (chopped)
• 240 ml wine vinegar (white plus)
• 120 ml bottled mayonnaise
• 60 gr gingerroot (grated fresh)
• 30 gr pickled ginger available in (finely chopped)
• 60 ml seasoned rice vinegar available in most
• 26 gr scallion (finely chopped)