Preheat your oven to 350°F. Grease an 8x8-inch pan or line it with parchment paper if you're feeling fancy.
In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, and salt. Give it a good stir—we're talking no lumps allowed.
Make three little wells in the dry ingredients. Pour vanilla into one, vinegar into another, and oil into the third. It’s like building a chocolate volcano.
Now pour the water over everything and stir until the batter is smooth and consistent. Don’t overthink it—just mix until you don’t see flour anymore.
Pour the batter into the pan and pop it into the oven. Bake for about 30 minutes, or until a toothpick in the center comes out clean.
Cool in the pan if you can resist digging in immediately. Slice, serve, or just grab a fork and go for it. No judgment here.