Cook rice according to package directions, substituting 2 cups chicken broth for water; set aside.
Melt butter in a Dutch oven over medium-high heat; sauté onion, bell pepper, and celery 8 minutes or until vegetables are tender. Add garlic; sauté 1 minute.
Stir in stewed tomatoes and Cajun seasoning; reduce heat to low, and simmer, uncovered, 15 to 20 minutes. Add crawfish tails, and cook 5 minutes. Stir in 1 cup chopped green onions, cooked rice, and pepper. Garnish, if desired.