Don't be afraid to use almost black bananas (ripeness improves the flavor) and refrigerate cake for 24 hours before serving for peak taste experience. Mix water, vinegar and soda. Combine with cake mix and eggs. Stir until moistened. Scrape bowl with spatula. Add mashed bananas. Beat with electric mixer 3 minutes at medium speed (300 strokes by hand). Blend in nuts. Pour into greased and floured 9x13 inch pan. Bake at 180ºC for 35 minutes (until toothpick comes out clean). VARIATION: Two 23 cm layers baking time 25 minutes Three 20 cm layers baking time 30 minutes.