Preheat the oven to 350°F. Spray an 8x8-inch baking pan with non-stick cooking spray.

In a large bowl, use a hand mixer on low speed to combine 1 cup flour, brown sugar, butter, orange peel, 1/2 teaspoon baking soda, and salt.

In a small bowl, whisk together the remaining 1 teaspoon baking soda and vinegar; the mixture will be fizzy. Add to the flour mixture and continue mixing just until combined.

In a medium bowl, add the remaining 1/4 cup flour, candied fruit mix, dates, and pecans. Stir to distribute the flour evenly. Add to the flour/brown sugar mixture and stir to combine. The batter will be thick; this is normal.

Transfer to the prepared baking pan, gently pressing with a spatula to distribute the batter evenly. Bake 35 minutes, or until a toothpick inserted in the center comes out clean. Cool completely then slice and serve at room temperature.