Hi Irene,
Dylan isn't allergic to soy so the recipe doesn't specifically exclude it, but you could definitely make it soy free. I use a vegan margarine in it, it's dairy free but contains soy. If you had a soy free margarine, or even coconut oil (isn't that semi-solid?) you could make it work!
3-4 Lg ripe bananas, mashed
1/2 cup sugar (the original recipe called for 1 cup but I reduced)
1/3 cup dairy free margarine, melted
1/4 cup applesauce
1 tsp vanilla (not necessary, I forgot to add it once and the muffins were still good!)
1 1/2 cup flour
1 tsp baking soda
1 tsp baking powder
1/2 tsp salt
Combine mashed banana, sugar, melted margarine, applesauce, and vanilla in mixing bowl, stir well. Combine flour, baking soda, baking powder, and salt in a separate bowl. Add to banana mixture, stirring well. Spoon into greased muffin tins and bake in a preheated oven at 350F. Bake 20m for regular sized muffins, 12-15m for mini muffins, or until a toothpick inserted in the centre of the muffin comes out clean.