Preheat oven to 400 degrees.
Grind flaxseed to a coarse powder in a blender or coffee grinder. In a bowl, sift together the flour, salt, sugar and baking powder. Stir in the flaxseed powder. In a separate bowl, beat together the eggs with the oil and milk. Add the liquid ingredients to the dry ingredients and combine with a few swift strokes. Stir the diced apples and the walnuts into the batter. Fill oiled muffin tins 2/3 full and bake for 20-25 minutes.
Makes 24-2" muffins.