Prepare the oven and baking dish. Preheat the oven to 375°F. Lightly coat an 8 × 8-inch baking dish with non-stick cooking spray, then place it aside until needed.
Sauté the vegetables. Melt the plant-based butter in a large skillet set over medium-high heat. Add the diced green bell pepper, yellow onion, and celery. Cook for approximately 2 minutes, or until the vegetables begin to soften.
Add the garlic. Stir the minced garlic into the softened vegetables and continue cooking for about 30 seconds. Stir frequently so the garlic does not scorch.
Lightly toast the rice and okra. Add the long-grain rice and sliced okra to the skillet. Cook for approximately 1 minute, stirring regularly, until the rice becomes very lightly toasted.
Season the mixture. Pour in the petite diced tomatoes along with all of their liquid. Add the Creole seasoning, salt, and black pepper, then stir thoroughly until the ingredients are evenly combined.
Assemble the casserole. Transfer the rice, okra, and vegetable mixture to the prepared baking dish. Pour the water evenly over the casserole so that the liquid is distributed throughout.
Cover and bake. Seal the baking dish tightly with aluminum foil to retain steam during cooking. Place it in the preheated oven and bake for 1 hour and 15 minutes, or until the rice is completely tender.
Finish and serve. Carefully remove the casserole from the oven and take off the foil. Gently fluff the cooked rice with a fork to separate the grains, then serve while hot.