In a jug, whisk the sunflower oil, eggs and yogurt. In a large bowl, combine the flour, bicarbonate of soda, cinnamon, sugar, walnuts and 1/2 tsp salt. Pour the wet ingredients into the dry, add pineapple, drain the sultanas and add these too, along with the carrots and banana. Mix with a spatula until combined, then scrape into the tin and bake on the middle shelf of the oven for 50 mins until a skewer inserted into the centre comes out clean. Cool in the tin for 10 mins, then transfer to a wire rack.