Preheat oven to 375 degrees.
Line 12 muffin cups with paper baking cups, or spray lightly with non stick cooking spray.
In a large bowl, whisk together the flour, baking soda, salt, and cinnamon.
In a medium bowl combine the mashed banana, sugar ,melted butter, eggs, and vanilla.
Add wet ingredients to dry and gently fold together until just combined.
Fold in strawberries.
Divide batter evenly, about ¾ full, between prepared muffin tins.
Bake for 15-18 minutes, until toothpick inserted in center comes out clean.
Remove from pan immediately to finish cooling.