• Rinse the rice.

In a small sauce pot, combine the rice and 1 cup [1½ cups] lightly salted water. Bring to a boil, reduce to a simmer, cover, and cook until the rice is tender and the liquid is absorbed, 15 to 20 minutes. Fluff with a fork, cover, and keep warm.
While the rice cooks, prepare the vegetables and cook the shrimp Creole.

• Peel and finely chop enough onion to measure 1 cup [2 cups].
• Trim the ends from the celery; cut the celery in half lengthwise, then thinly slice crosswise.
• Remove the stem, ribs, and seeds from the bell pepper. Cut the pepper lengthwise into ¼-inch-wide strips, then crosswise into ¼-inch pieces.

• Rinse the shrimp, then drain on a paper-towel-lined plate and pat dry. Season lightly with salt and pepper.

In a medium [large] sauce pot over medium-high heat, warm 2 to 3 teaspoons [4 to 5 tsp] oil until hot but not smoking. Add the onion, celery, bell pepper, and tomato paste, season with salt and pepper, and cook, stirring occasionally, until lightly browned, 2 to 3 minutes. Add the tomatoes, Creole seasoning, Worcestershire sauce, ½ cup [¾ cup] water, and as much cayenne as you like. Bring to a boil, reduce to a simmer, cover, and cook until the sauce is thickened slightly and the vegetables are just tender, 3 to 5 minutes.
Add the shrimp and cook until firm and cooked through, 3 to 4 minutes. Remove from the heat and season to taste with salt and pepper.
When the shrimp Creole is almost done, prepare the scallion garnish.

• Trim the root ends from the scallions; thinly slice the scallions on the diagonal.

Transfer the rice to the center of individual bowls. Spoon the shrimp Creole around the rice, sprinkle with the scallions, and serve.