Mix all dry ingredients. Puree the peeled banana in a blender and mix with the soy milk and oil. Now add the liquid ingredients to the dry ingredients and stir with the hand mixer for about 2 minutes. If the dough is too firm, add a little more soy milk.
Divide the dough into four equal parts and color each part with a different color to suit your taste. Fill the muffin cups three-quarters full, approx. 1 tablespoon full of each color.
Bake in the hot oven for about 22 minutes on the middle rack. Please do with a chopstick test.
This amount of dough is sufficient for approx. 10 - 12 muffins.