Preparation

• Combine the plant-based milk and apple cider vinegar in a bowl and let it sit for 5 minutes—this curdling process creates a vegan buttermilk that will add tanginess and help the cake rise. While this sits, whisk together the oil, applesauce, sugar, vanilla extract, and orange zest in another bowl until well combined. After the milk has curdled, pour it into the wet ingredient mixture and stir to combine. This two-component approach prevents the vinegar from prematurely reacting with the dry ingredients.
• Preheat your oven to 350°F. While it heats, whisk together the all-purpose flour, baking powder, salt, cinnamon, and ground nutmeg in a separate bowl. Set the dry mixture aside until ready to combine.
• Prepare a 9-inch round cake pan by melting the vegan butter and brushing it evenly across the bottom and sides. Sprinkle the brown sugar over the butter to create an even, caramelized base layer.
• Combine the hulled and sliced strawberries with the rhubarb pieces in a bowl, gently tossing to mix. Arrange them in an even layer over the butter and brown sugar base.
• Fold the dry ingredient mixture into the wet ingredient mixture using a spatula or wooden spoon, mixing just until the flour is incorporated. Gently pour and spread the batter evenly over the prepared fruit layer.
• Bake for 35-40 minutes, until a toothpick inserted into the cake portion comes out clean and the top is lightly golden brown. Remove from the oven and let cool for exactly 5 minutes before inverting onto a serving plate.