Preheat the oven to 350 degrees F (175 degrees C). Grease and flour a 9x5-inch loaf pan.

Combine flour, baking soda, cinnamon, and salt in a bowl. Add sugar, oil, eggs, and vanilla extract. Add shredded apples and chopped nuts. Mix until combined. Set aside.

For the streusel: Mix sugar, cinnamon, and flour together in a bowl. Cut in butter until mixture is crumbly. Place 1/2 of the streusel on the bottom of the prepared loaf pan. Pour in batter and top with remaining streusel.

Bake in the preheated oven until a toothpick inserted into the center comes out clean, 60 to 75 minutes. Cool on a wire rack for 10 minutes before removing from the pan.