1. In a medium saucepan, bring water to a boil over high heat. Add rice and let water return to a boil, then reduce heat to low, cover, and simmer 5 minutes. Remove from heat, stir, then cover and let rest.
2. Place shrimp in a colander and run cold water over them, tossing occasionally to ensure that they are all exposed to the water, until they are thawed and bendable, about 6 minutes. Pat shrimp dry with a paper towel and toss with 1 tsp. of the Cajun seasoning rub. Set aside.
3. Chop onion, celery, and bell pepper. Heat oil in a large nonstick skillet over medium-high heat. Add chopped vegetables and cook, stirring, until they begin to soften, about 4 minutes. Add garlic and cook, stirring, for 30 seconds.
4. Add tomato paste and cook, stirring to coat vegetables, until paste begins to caramelize lightly, about 60 to 90 seconds. Add tomatoes, water, sugar if using, remaining 1 tsp. Cajun seasoning, and cayenne. Bring to a boil. Reduce heat and simmer for 5 minutes.
5. Thinly slice white part and beginning of green of the scallions. Add to skillet with the shrimp and cook until shrimp is done, about 5 minutes. While shrimp cook, thinly slice scallion greens.
6. To serve, divide rice among 4 bowls and top with shrimp and vegetables. Garnish with scallion greens.
Source: Hannaford fresh Magazine, March - April 2015