Preheat oven to 375 degrees F (190 degrees C). Grease and flour a muffin pan, or use paper liners. In a small bowl, combine oats and buttermilk, and let stand 5 minutes. In a medium bowl, combine flour, baking powder, baking soda and salt; set aside.
In a large bowl, beat together the egg, oil, brown sugar and vanilla. Blend in the oat mixture. Stir in the flour mixture, just until moistened. Fold in strawberries. Fill muffin cups 2/3 to 3/4 full.
Bake in the preheated oven for 15 to 20 minutes, or until a toothpick inserted into the center comes out clean.