Make Filling - Reduce heat to medium and add onions, bell pepper, and remaining oil into the same pot, Stir and cook until tender but not browned, 6-8 minutes. Season with salt and pepper. Stir in cumin, oregano, cayenne, and paprika. Cook about 1 minute more until fragrant. Add beef and its juices to the pot along with chicken stock. Stir in sugar, salt, and black pepper. Bring to a simmer and cook, stirring occasionally, until most of the liquid has evaporated, about 15-20 minutes. Stir in raisins and, if using, chopped eggs. Transfer to the bowl the meat was in. Adjust seasoning, cover, and chill at least 3 hours and up-to 3 days.