Preheat oven to 350 degrees. In a small bowl add the apple cider vinegar into the oat milk (or your choice of nut milk)and set aside.
Add 3 tablespoons vegan margarine to a 9-inch round springform pan. Use a pastry brush to brush coat the sides and bottom of pan with the margarine. Sprinkle 1/4 cup of the sugar on top.
Arrange peaches in a circle at edge of skillet, on top of sugar. Arrange the remaining wedges in the center to fill; set aside.
Whisk cornmeal, flour, baking powder, baking soda, and and salt in a medium bowl.
Beat remaining margarine and 3/4 cup sugar with a mixer on high speed, until pale and fluffy, about 3 minutes. Reduce speed to medium. Add apple sauce and vanilla and mix on low. Add in the oat milk. Beat in cornmeal mixture in 2 additions.
Drop large spoonfuls of batter over peaches, and spread evenly using an offset spatula. Bake until golden brown and a tester inserted in the center comes out clean, 25-30 minutes.
Transfer skillet to a wire rack, and let stand for 10 minutes. Run a knife or spatula around edge of cake. Quickly invert cake onto a cutting board or your cake plate. Tap bottom of pan to release peaches, and carefully remove skillet. In case you lose some peaches, you can reposition peach slices on top of cake. We like it best when it’s warm and even better with a scoop of dairy-free vanilla ice-cream.