Heat the canola oil in an 8-quart Dutch oven or heavy soup pot over medium-high heat. Add the bell peppers, onion, celery, and garlic, and sprinkle with salt. Cook 10-12 minutes, stirring occasionally, until soft. Stir in the white pepper, black pepper, thyme, oregano, and cayenne, and cook 1-2 minutes, until fragrant. Add the kidney beans and ham hocks, and cover with 6 cups of water. Stir to combine. Bring to a boil, then add the bay leaves and reduce heat to medium-low. Cover and cook for about 2 hours, until the beans and ham hocks are tender. Transfer the ham hocks to a cutting board and remove and discard the bones and skin. Finely chop the meat and return to the pot. Stir in the hot sauce. Serve ladled over white rice, and garnish with scallions.