Preheat your oven to 350°F (175°C) and spray a loaf pan with nonstick spray.
In a bowl, mix flour, baking soda, cinnamon, and salt.
In another bowl, cream together butter and sugar until light and fluffy.
Add eggs, vanilla, and sour cream to the butter mixture, then stir in mashed bananas.
Gently fold in the dry ingredients until just combined.
Add diced strawberries and chopped nuts; mix lightly without over-stirring.
Pour batter into the greased loaf pan and smooth the top.
Bake for 50–55 minutes or until a toothpick comes out clean. Let cool before slicing.