In a large mixing bowl, combine the 3 cups of all-purpose flour and 1/2 teaspoon of salt. Whisk together to ensure the salt is evenly distributed. Add in the 3/4 cup of vegetable oil and mix until the mixture resembles coarse crumbs.
Gradually pour in the 1/2 cup of cold water, mixing until a dough forms. You may need to adjust the water slightly to achieve the right consistency. Knead the dough on a floured surface for about 5 minutes until smooth. Wrap it in plastic wrap and let it rest for 30 minutes.
While the dough is resting, heat a tablespoon of oil in a skillet over medium heat. Add the diced onion and red bell pepper, sautéing until the onion is translucent, about 5 minutes. Add the minced garlic, cumin, paprika, and black pepper, stirring for another minute until fragrant.
Remove the skillet from heat and stir in the cooked black beans, corn, and chopped cilantro. Mix well and set aside to cool slightly.
After the dough has rested, preheat your oven to 375°F (190°C). On a floured surface, roll out the dough to about 1/8-inch thick. Use a cookie cutter or a glass to cut out circles, approximately 4-5 inches in diameter.
Place a tablespoon of filling on one half of each dough circle. Be careful not to overfill them! Fold the dough over to create a half-moon shape and press the edges together. Use a fork to crimp the edges for a decorative touch.
Place the empanadas on a baking sheet lined with parchment paper. Optionally, brush the tops with a little vegetable oil for a golden finish. Bake for 20-25 minutes or until they are golden brown.
Once baked, let the Vegan Empanadas cool slightly before serving. They can be enjoyed warm or at room temperature, making them perfect for any occasion!