In a large bowl mix the flour, salt, sugar and the walnuts. Separately, mix mashed mashed bananas, lightly beaten with a fork eggs, yogurt, which has previously placed soda, melted and cooled butter and vanilla extract. Liquid products are poured into the flour mixture and gently stir with a wooden spoon (spatula), while only dry take liquid (4-5 times). The batter was poured into pre-greased and floured cake pan (24 cm diameter with a hole). Bake in preheated oven at 180 C for 55 minutes (readiness check with a toothpick). Serve warm or chilled.