In a medium bowl, combine 1/3 cup vinegar and 1/4 teaspoon salt. Place the onion in a small saucepan with enough water to cover. Bring to a boil, drain and transfer to the vinegar solution.
Meanwhile, preheat the oven to 200 degrees . Line a baking sheet with paper towels. In a large nonstick skillet, heat 3 tablespoons oil over medium-high heat. Working in batches, fry the plantains, 2 minutes per side. Drain on the prepared baking sheet and transfer the baking sheet to the oven. Wipe out the skillet and reserve.
Using a food processor, process the tortillas until finely ground; transfer to a plate and wipe out the food processor. In a large, shallow bowl, beat the eggs. Season the pork chops with salt and pepper. Working with 1 at a time, dip the pork chops in the egg, letting the excess drip off, then coat with the tortilla crumbs.
In the reserved skillet, heat 2 tablespoons oil over medium heat. Working in 2 batches, wiping out the skillet and using fresh oil with each batch, cook the pork chops until golden, about 6 minutes per side; transfer to the oven to keep warm.
Meanwhile, using the food processor, puree half of the black beans with the remaining 2 tablespoons vinegar, the brown sugar and 1/4 cup water. In a medium saucepan, toast the chili powder over low heat until fragrant, 1 minute. Add the pureed bean mixture and the remaining beans and cook over medium-high heat, stirring occasionally, until heated through. To serve, top the pork chops with the pickled red onion and serve with the black beans and fried plantains.