For the banana bread grease a box form (approx. 25 cm long; 1.5 l capacity). Preheat the oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2). Roast the coconut flakes in a pan without fat until golden brown. Take out. Coarsely chop the nuts. Peel bananas and weigh 450 g of fruit flesh. Mash with a fork
Cream banana puree, sugar, eggs and buttermilk with the whisk of the mixer. Mix flour, baking powder and 1 pinch of salt, sift over it and stir in. Fold in nuts and coconut flakes. Smooth the dough in the form. Bake bread in the oven for 35-45 minutes. Leave to cool in the tin for about 10 minutes, turn out onto a cake rack and let it cool completely
For the sashimi, cut off 8 thin slices of bread (use the rest of the bread for other purposes). Cut out or cut slices of bread as circles as you like. Fry in hot oil until crispy brown on each side. Drain on kitchen paper
Peel the mango and cut the flesh into slices from the stone. Cut the avocado in half and remove the flesh. Finely dice mango, avocado and tuna, mix loosely. Mix soy sauce, 5 tbsp. water, chilli sauce, sesame oil and lime juice, drizzle over the mixture. Arrange sashimi immediately with roe on the crostini and serve