In a glass or ceramic bowl, toss the okra with the lemon juice. Let sit for 15 minutes.
In a large heavy saucepan, heat the olive oil over high heat. Saute the okra for 4 to 5 minutes, stirring frequently, until golden. Add the onion, reduce the heat to medium, and cook for 6 to 8 minutes, until softened. Add the green pepper and the garlic and cook for 2 minutes more, until the garlic releases its aroma. Add the tomatoes, cook for 2 minutes, stirring, and add the sherry, salt, and pepper. Cook the mixture for 5 minutes, stirring occasionally, until thickened.
Increase the heat to medium, add the rice, saffron, corn, drained okra, and chipotle. Stir the mixture well and cook for 2 minutes. Add the pickling liquid and the chicken broth, stir again and cook partially covered for 15 to 20 minutes, until most of the liquid has been absorbed and small craters form in the top of the rice. Stir with a fork and cover the pan. Reduce the heat to low and simmer for 10 to 15 minutes more, until the rice is tender.
To pickle chipotle chiles, combine 6 dried, stemmed chipotles with 2 cups red wine vinegar in a small pan. Bring to a boil, reduce to a simmer and cook, covered, for 5 minutes. Set aside to cool. Transfer to a clean jar and store in the refrigerator for up to 3 months.