In large bowl, mix together flour, sugar, salt, and baking powder.
In a separate bowl, mix oil, egg, milk and 1/2 cup applesauce until smooth.
Slowly, add liquid mixture to flour mixture, stirring continuously.
Continue stirring until just moistened. (Note: you might have to add an additional 1/4 cup of applesauce - the batter should be thick, similar to brownie batter).
Gently, fold in blueberries until incorporated.
Spoon the batter into the muffin cups or liners, filling them approximately 2/3 full.
Bake muffins at 400 degrees, until golden brown - approximately 20 minutes.
The muffins are done when a toothpick inserted in the center comes out clean.
Notes
Nutrition calculated using My Fitness Pal's recipe calculator and ingredients used. Please recalculate nutrition with your specific ingredients.