Source: Joy of Cooking

Preheat the oven to 350F. Grease and flour one 8X8-inch pan.

Whisk together thoroughly in a large bowl:

• 1 1/2 c all-purpose flour
• 1 c sugar
• 1tsp baking soda
• 1/2 tsp salt

Add and stir together until smooth:

• 1c orange juice
• 1/3 c vegetable oil
• 1 Tbsp grated orange zest
• 1 Tbsp white or cider vinegar
• 1tsp vanilla

Scrape the batter into the pan and spread evenly. Bake until a toothpick inserted into the center comes out clean, 30-35 min.