Steam Blueberry Cake

This is the 1st time I did a blueberry cake but the result was not good as It is quite hard and had a strong flour taste. It could be I misplaced any step or what, but I am not sure. I prefer the later version Steam Blueberry Walnut Cake. I found that recipe better for me.

Ingredients:-

•   3/4 cup(s) plain flour   
•   1/4 cup(s) wholemeal plain flour   
•   1/2 tsp bicarbonate of soda, (bicarbonate of soda)   
•   1 small egg(s), lightly beaten   
•   1/2 tbs low-fat vanilla yoghurt   
•   2 tbs canola oil   
•   1 tsp vanilla bean extract(Not added as I cannot get it)   
•   1 cup(s) fresh blueberries   
•   1 tbs icing mixture   
•   1/3 cup(s) caster sugar   
•   1 1/2 tsp baking powder   
•   1/4 tsp ground cinnamon (Not added as I cannot get it)  
•   1/4 cup(s) skim milk   

Instructions:-

1. Combine both flours, sugar, baking soda (bicarbonate of soda), baking powder, cinnamon and a pinch of salt in a large bowl. Combine egg, milk, yoghurt, oil and vanilla in a separate small bowl. Stir well until combined. Make a well in flour and fold through egg mixture until well combined. Carefully stir through blueberries.
2. Spray a 1-litre capacity souffle dish with oil. Spoon cake batter into dish and level with back of spoon. Spray a sheet of foil with oil and cover dish tightly, oil side down, so that cake is water tight.
3. Pour 3 cups boiling water into base of a large saucepan. Place cake in bottom of saucepan, cover and simmer on a very low heat for 1 1/2 hours. You may need to add more boiling water during cooking process, so keep a check on water levels. Test cake with a cake skwewer and, when cooked, carefully remove from saucepan. Allow to stand for 5 minutes before turning out onto a cake rack. Sprinkle with icing sugar and serve.
4. Cut into wedges and accompany with low-fat vanilla custard if desired