In a medium saucepan with a tight-fitting lid, combine 3 cups water, rice, and ½ tablespoon salt. Bring to a boil over medium-high heat, stirring occasionally. Reduce heat, and simmer, covered, until water is absorbed, 15 to 20 minutes. Remove from heat, and let cool for 5 minutes. Strain into a colander, and rinse with cool water. Spread rice onto a rimmed baking sheet, and let stand until cool.
Preheat oven to 350°. Line a rimmed baking sheet with parchment paper. Place pecans on prepared pan. Bake until toasted, 5 to 8 minutes. Let cool on a wire rack.
In a medium saucepan, heat 1 tablespoon oil over medium heat. Add yellow onion and celery; cook, stirring frequently, until fragrant and translucent, about 3 minutes. Add edamame, green onion, mint, parsley, black pepper, and remaining ½ tablespoon salt; cook for 2 minutes, stirring constantly. Remove from heat, and transfer to a large bowl. Stir in bell pepper, rice, and pecans.
In a small bowl, whisk together vinegar, lemon juice, and remaining ¼ cup oil. Pour over rice mixture. Using 2 forks, fluff rice. Garnish with mint and parsley, if desired. Serve immediately.
Recipe by Louisiana Cookin' at https://louisianacookin.com/rice-salad/