Roughly chop the onion, squash, peppers, and celery. Pulse in a food processor to mince. Heat 3 tablespoons of the oil in a large saucepan over medium-high heat. Add the minced vegetables, 1 teaspoon of the salt, and the cayenne. Cook, stirring frequently, until the vegetables are soft and the liquid has evaporated, about 5 minutes. Add the tomatoes, Worcestershire, and hot sauce. Bring the liquid to a boil, reduce heat, and simmer about 25 minutes, stirring frequently. Meanwhile, prepare the rice according to the package directions. Season both sides of the tuna with the remaining 1/2 teaspoon of salt and the black pepper. Heat the remaining oil in a large skillet and sear the tuna on both sides, working in batches if necessary, until the flesh is just pink in the center, about 6 minutes total. Arrange the tuna over the rice and cover with the Creole vegetable sauce.