Preheat the oven to 350˚F (180˚C). Line a baking sheet with parchment paper.
In a large bowl, whisk together the flour, sugar, and baking powder. Add the corn oil, vanilla, and eggs, and stir with a rubber spatula until the dough starts to come together. Use your hands to finish mixing the dough until well combined and thick.
If making strawberry mandelbrot, wet your hands with water and shape half of the dough into a rough oval on the prepared baking sheets. Pinch the edges of the dough up to create a well. Spread the strawberry jam in the center of the dough. Flatten the remaining dough and place on top of the strawberry jam. Leave a bit of extra dough in the bowl to fill in the cracks.
If making chocolate chip mandelbrot, fold the chocolate chips into the dough. Wet your hands with water and shape the dough into a rough oval on the prepared baking sheet.
Bake the mandelbrot for 25-35 minutes, or until the edges are golden brown.
Let cool for 10 minutes, then transfer to a cutting board. Top with cinnamon sugar, if desired, then slice into 1-inch-wide pieces.
Serve with additional strawberry jam, whipped cream, coffee, or ice cream, if desired.