Preparation Cook onions in oil in a 4-quart heavy pot over medium heat, stirring occasionally, until golden brown, 15 to 20 minutes. Pat meat dry and toss with 1 teaspoon salt. Increase heat to high, then add meat, saffron, and turmeric to onions and cook, stirring frequently, until meat is no longer pink, about 5 minutes. Stir in water and tomatoes, then simmer, covered, 1 hour. Stir in split peas, tomato paste, Omani lemons (if using), cinnamon, allspice, and 1/2 teaspoon pepper and simmer, covered, stirring occasionally, until meat is very tender, 1 to 1 1/4 hours more. Discard Omani lemons and stir in salt and Key lime juice to taste.
Preparation Cook onions in oil in a 4-quart heavy pot over medium heat, stirring occasionally, until golden brown, 15 to 20 minutes. Pat meat dry and toss with 1 teaspoon salt. Increase heat to high, then add meat, saffron, and turmeric to onions and cook, stirring frequently, until meat is no longer pink, about 5 minutes. Stir in water and tomatoes, then simmer, covered, 1 hour. Stir in split peas, tomato paste, Omani lemons (if using), cinnamon, allspice, and 1/2 teaspoon pepper and simmer, covered, stirring occasionally, until meat is very tender, 1 to 1 1/4 hours more. Discard Omani lemons and stir in salt and Key lime juice to taste.