Preheat the oven to 350 degrees F (175 degrees C). Spray a 9x5-inch loaf pan with nonstick spray. Line a baking sheet with parchment paper.

Sift flour, baking soda, cinnamon, and salt together into a bowl.

Beat sugar and butter together in a large bowl until lighter in color. Mix in sour cream, eggs, and vanilla. Add mashed bananas and mix until combined. Gradually mix in dry ingredients. Fold in strawberries and nuts. Pour into the prepared pan and set on the lined baking sheet.

Bake in the preheated oven until golden brown and a toothpick inserted in the center comes out clean, 65 to 80 minutes.