Preheat oven to 350°F. Grease muffin pans with nonstick cooking spray or line them with liners. Be sure to spray liners with nonstick cooking spray as well.
Stir oil, salt, and 3/4 cup sugar with a wooden spoon. Set aside.
Add bananas, eggs, almondmilk, vanilla, baking soda, and vinegar to a blender jar and blend until smooth.
Stir the banana mixture into the sugar mixture, then stir in the flour until just combined. Stir in blueberries. (Make sure that your frozen berries are not overly wet; pat them dry and/or remove any ice crystals or your batter will be too wet.)
Fill muffin cups 3/4 full (about 1/4 cup of batter per muffin).
Optional topping: stir 2 tablespoons sugar and cinnamon, then sprinkle on the top of the muffins.
Bake for 15-20 minutes until a toothpick comes out clean. Cool at least 10 minutes before removing muffins from pan.