Bring 4 cups water to a boil in a 4-qt. heavy saucepan. Add rice and 1/2 teaspoons salt and cook, covered, over low heat until water is absorbed and rice is tender, about 20 minutes. Remove from heat and let stand, covered for 10 minutes, then fluff rice with a fork and keep covered.
Meanwhile, heat 1 tablespoons oil in a 10-12 inch heavy skillet, preferably cast-iron, over moderately high heat until hot, but not smoking. Add sausage, in two batches, and cook stirring occasionally, until browned, 2-3 minutes per batch; transfer with a slotted spoon to a bowl. Add okra to skillet and cook, stirring occasionally, until browned, 2-3 minutes. Transfer to another bowl.
Heat remaining tablespoons of oil in skillet over moderately high heat until hot, but not smoking. Add onions and bell peppers and cook, stirring occasionally, until softened and browned, about 5 minutes. Add garlic and cook, stirring, for 1 minute. Add okra, stock, remaining 1/4 cup water, 1 teaspoons salt, and pepper, bring to a simmer, and simmer, uncovered, stirring occasionally until liquid is slightly thickened and reduced to just below surface of solids, 10-12 minutes.
Stir in sausage and toss with rice , scallions, and salt and pepper to taste.