1. To make flax egg, in a food processor or blender, grind the flax seeds until they are a fine flax meal. Slowly add the water until the mixture has a thick milk shake like consistency. Use 1/2 of mixture for 3 eggs.
2. Add grated sweet potatoes and onion to large bowl.
3. Add baking powder, flour, flax eggs, salt and pepper, and stir/mix very well.
4. Cover a pan with a thin layer of oil. Form cookie sized pancakes, and fry until golden on both sides.