Preheat the oven to 350°F.

Put the sugar in a large sauté pan and heat over medium heat, stirring continuously, for 5 to 6 minutes, until the sugar melts and forms a caramel: you’re looking for a light golden color. Be careful to not let it get too dark, which will taste bitter. Immediately pour the caramel into a 10- to 12-cup Bundt pan and, using oven mitts, pick up the pan and swirl it around to evenly coat the bottom with the caramel. Set aside.

Combine the silken tofu, vegan condensed milk, milk, vanilla, and salt in a blender and blend on high for 1 minute, or until smooth. Hold a fine-mesh sifter over the blender and sift the cornstarch, agar agar powder, and turmeric into the blender. Blend on high for 1 minute. Using a spatula, scrape the walls of the blender to ensure all the cornstarch gets blended in. Blend again for 10 seconds, then pour the contents of the blender into the Bundt pan.

To make a water bath, place the Bundt pan in a large baking dish with high sides—ideally almost as tall as the Bundt pan. Pull the oven rack out and place the baking dish and Bundt pan on the rack, then carefully pour water into the baking dish so it comes about halfway up the sides of the Bundt pan.

Bake for 1 hour. Remove the Bundt pan from the oven, leaving the water bath in the oven and the oven on.

Follow the instructions on the cake mix box to make the batter, substituting plant-based ingredients as necessary and adding the vinegar. Slowly pour the batter over the baked flan.

Carefully place the Bundt pan back into the water bath in the oven and bake for 50 minutes. Check for doneness by sticking a toothpick in the middle—it should come out clean. If not, bake for another 10 to 15 minutes.

Let the chocoflan cool for 2 hours, then cover with aluminum foil and refrigerate for at least 6 hours.

When ready to serve, run a kitchen towel under hot water and squeeze mostly dry. Lay the hot dampened towel on the counter and place the Bundt pan on top, lifting the towel up to surround the base of the Bundt pan and warm the surface. This will help melt the caramel layer. Keep the towel there for a minute.

Remove the foil and carefully run a butter knife around the edges of the chocoflan. Place a large serving dish upside down over the pan, then carefully flip the pan onto the plate. Set the plate on the counter and carefully lift the pan to release the chocoflan. You may have to wiggle it a tiny bit to release.