Heat 1 tablespoon olive oil in a saucepan over medium heat. Add the onion and celery; cook, stirring, until softened, 4 minutes. Add the garlic and cook 1 minute. Add the rice and Cajun seasoning and cook, stirring, until lightly toasted, about 1 minute. Increase the heat to medium high; stir in 2 cups water and 3/4 teaspoon salt. Bring to a simmer, then reduce the heat to low; cover and cook until tender, about 15 minutes. Uncover and set aside.
Wrap the tofu in paper towels and set on a plate. Weigh down with a bowl; let drain 10 minutes. Cut in half lengthwise, then slice 1/2 inch thick.
Heat a large nonstick skillet over medium-high heat. Add 1 tablespoon olive oil, the bell peppers, and salt and pepper to taste. Cook, stirring, until the peppers start browning, 4 minutes; transfer to a plate.
Add the remaining 1 tablespoon olive oil and the tofu to the skillet in a single layer. Cook until browned, about 4 minutes per side. Stir in the bell peppers, barbecue sauce and scallions. Stir the parsley into the rice; top with the tofu.